# **Idle Cross: Permanent Nightmare Mode**
## **Chapter 2: The Video Game of Demon Slayer**
Den disappeared into the Black Star.
Darkness surrounded his entire body, but this darkness felt different from the darkness he controlled.
His own darkness obeyed him.
This darkness was like a tunnel between universes.
Colors, broken images, strange symbols, and pieces of different worlds passed around Den. He saw a pixelated castle, a burning city, several floating islands, and something that looked like a smiling flower with teeth.
Den looked at the flower.
The flower looked at Den.
Den slowly raised one hand.
The flower immediately disappeared into another portal.
"Smart flower."
Den continued falling through the pathway between realms.
There was no gravity, but he still felt like he was falling. His Villain Armor protected him from the pressure around his body while the broken Villain Halo behind his head glowed darker.
A new screen suddenly appeared.
**Ding!**
**The host has entered an unknown Black Star pathway.**
**Scanning connected realm...**
**Scan completed.**
### **Connected Realm Identified**
**Demon Slayer: Kimetsu no Yaiba — The Hinokami Chronicles**
**Realm Classification: Video-Game-Based Universe**
**Main Story Progress: Final Selection**
**Realm Stability: 94%**
**Estimated Realm Difficulty Without Host Restrictions: Irrelevant**
**Estimated Realm Difficulty With Host Restricted to 0.00000001% Power: Low**
Den stared at the last two lines.
"Low?"
He crossed his arms.
"How weak do I have to become before someone gives me a good fight?"
The system did not answer.
Another screen appeared.
### **Warning**
**The laws of this universe operate differently from the previous realm.**
* Certain characters possess visible health and stamina values.
* Combat areas may create temporary invisible boundaries.
* Defeated game characters may occasionally return after a story reset.
* Important story characters possess limited protection against accidental death.
* This protection does not defend them against deliberate execution.
* Demons may recover health through regeneration.
* Demons remain vulnerable to sunlight and specialized weapons.
* The host is not restricted by the game's rules.
* The host may damage the game's interface, boundaries, map, story progression, and save data.
Den's smile slowly returned.
"So I can punch the game itself?"
**Ding!**
**Yes.**
"Best system feature so far."
The darkness around him shook.
Far ahead, a new portal opened.
Before Den entered it, the Mission Tab automatically appeared.
### **New Realm Mission Chain Unlocked**
# **Main Mission 2: Enemy of Everyone**
**Make both the Demon Slayer Corps and the demons recognize the host as a major threat.**
### **Objectives**
* Defeat 20 Demon Slayers: **0/20**
* Defeat 100 Demons: **0/100**
* Defeat one Hashira: **0/1**
* Make a member of the Twelve Kizuki fear the host: **0/1**
* Receive an official kill-on-sight order from both factions: **0/2**
### **Rewards**
* High-Level Perk: **Combat Evolution**
* Special Weapon: **Starless Nichirin**
* Special Title: **Enemy of Both Sides**
* Three random villain perks
* One realm travel coordinate
Den read the objectives.
He was quiet for a few seconds.
Then he nodded.
"That sounds reasonable."
Another mission appeared.
# **Special Mission: The Worst Tutorial Guest**
**Interrupt Final Selection and defeat its boss without using dark magic, clones, ranged attacks, or more than 0.00000001% of the host's physical power.**
### **Bonus Objectives**
* Defeat the boss primarily through hand-to-hand combat.
* Allow the boss to regenerate at least ten times.
* Make the boss ask a human for help.
* Complete the battle without receiving damage.
* Kill the boss using sunlight instead of a Nichirin sword.
### **Rewards**
* Special Perk: **Demon Combat Instinct**
* Special Ability: **Bloodless Demon Art Creation**
* Physical power control improved by 1,000%
* One random combat talent
Den's white eyes narrowed with interest.
The first mission wanted destruction.
The second wanted skill.
He liked the second one more.
A third mission appeared.
# **Side Mission: Borrowed Sword**
**Take a Nichirin sword from a living Demon Slayer and defeat its owner using their own weapon.**
### **Restrictions**
* The owner must survive the first defeat.
* The host cannot use more than the physical strength of the sword's owner during the sword battle.
* Dark magic is prohibited during the duel.
### **Rewards**
* Talent: **Perfect Sword Comprehension**
* Perk: **Weapon Theft Mastery**
* The stolen sword may be permanently upgraded.
Den raised one eyebrow.
"The owner has to survive the first defeat?"
The wording was very specific.
Den already understood the loophole.
The owner only needed to survive the first defeat.
What happened afterward was apparently not the system's concern.
Another mission followed.
# **Hidden Villain Mission: Bad First Impression**
**Make Tanjiro Kamado personally decide that the host is more dangerous than a normal demon.**
### **Bonus Objectives**
* Terrify Tanjiro without threatening his sister.
* Defeat Tanjiro in hand-to-hand combat.
* Defeat Tanjiro in sword combat.
* Demonstrate a demon-style combat ability.
* Leave him alive for reasons other than mercy.
### **Rewards**
* Villain Presence upgraded.
* Fear Absorber upgraded.
* Unlock one future Tanjiro-related mission.
Den smiled.
"That last part understands me already."
He did not need to kill everyone he met.
Sometimes leaving someone alive was worse.
Dead enemies could not become stronger.
Dead enemies could not spread fear.
Dead enemies could not spend every night remembering how easily Den could have ended them.
Death was useful.
Survival could be more entertaining.
The portal opened completely.
Den entered it.
---
### **Final Selection**
A dark forest appeared beneath him.
Den dropped out of the Black Star and landed between several enormous trees.
His feet touched the ground gently.
Even with that gentle landing, the dirt sank several inches beneath his shoes.
Purple wisteria flowers surrounded the mountain's lower areas, but deeper inside the forest there were no flowers.
The air smelled of blood.
Human blood.
Demon blood.
Fear.
A lot of fear.
Den inhaled slowly.
Fear Absorber immediately reacted.
Thin streams of energy moved toward him from across the mountain. Most came from young Demon Slayer candidates attempting to survive Final Selection.
Some candidates were hiding.
Some were fighting.
Some were already dying.
Den could hear swords colliding with claws.
He heard bones breaking.
He heard someone screaming for help.
He also heard a man yelling something about becoming the strongest while running in the opposite direction of a demon.
Den looked toward the sound.
"That one has confidence and survival instincts fighting each other."
His vision expanded across the mountain.
Health bars appeared above every living creature.
Names floated above important characters.
Small blue bars represented stamina.
Red bars represented health.
Demons possessed additional regeneration meters.
Several candidates had glowing yellow markers above their heads.
One marker was brighter than the others.
### **Tanjiro Kamado**
**Story Character**
**Current Objective: Survive Final Selection**
**Current Emotional State: Focused, worried and determined**
**Current Health: 78%**
Den found Tanjiro several kilometers away.
The boy was fighting a huge demon covered in arms.
The demon's body was green, swollen, and wrapped in dozens of thick limbs. Several arms protected its neck while others struck at Tanjiro from different directions.
A giant health bar stretched across the sky above it.
# **HAND DEMON**
### **Tutorial Boss**
The Hand Demon roared.
Tanjiro moved beneath one arm, cut through another, and narrowly avoided being crushed against the ground.
Den watched the battle for three seconds.
Then an enormous symbol appeared in front of his face.
### **TUTORIAL**
**Press Light Attack to perform a basic attack.**
Den stared at the message.
"Move."
The message remained in front of him.
**Press Light Attack to perform a basic attack.**
Den waved his hand through it.
The tutorial window shattered.
Pieces of glowing text fell to the ground.
The pieces exploded.
**Ding!**
**The host has destroyed a tutorial interface.**
**Minor reward acquired: +1% resistance against forced instructions.**
Den looked at the remaining pieces.
"You can get rewards for breaking menus?"
The forest suddenly became much more interesting.
A scream came from the battlefield.
The Hand Demon slammed Tanjiro through several trees.
Tanjiro struck the ground, rolled, and barely managed to rise before another group of arms reached toward him.
Den activated complete power control.
### **Physical Output Restriction**
**Current Output: 0.00000001%**
His power compressed.
The pressure surrounding him disappeared.
His speed, strength, and defense decreased to a level the realm could survive.
Den rotated his shoulders.
He lowered his stance.
His left foot moved forward.
His hands relaxed.
Yin and Yang Combat Skills automatically adjusted his posture for the Hand Demon's body structure.
The demon possessed many arms.
That meant it had many weapons.
It also meant it had many joints.
Many joints meant many things to break.
Den vanished.
---
Tanjiro saw another hand approaching his face.
He moved his sword upward.
He was too slow.
The Hand Demon's palm was already directly in front of him.
Then someone stepped between them.
A young man wearing black armor appeared without warning.
A broken dark halo floated behind his head.
His skin was completely black.
His eyes were completely white.
He looked human.
But Tanjiro smelled something wrong.
The stranger did not smell like a demon.
He did not smell human either.
There was darkness around him.
Fear.
Blood.
Smoke.
And something that reminded Tanjiro of a gigantic empty space where nothing living should exist.
The Hand Demon's palm struck Den.
Or it tried to.
Den caught one of its fingers.
The difference in size was ridiculous.
The finger was thicker than Den's arm.
Den twisted it.
**CRACK!**
The finger bent backward.
The Hand Demon screamed.
Den continued twisting.
The entire arm rotated.
Bones broke one after another until the limb wrapped around itself.
The Hand Demon pulled away.
Den did not release it.
Instead, he stepped forward and drove his shoulder into the demon's elbow.
The joint snapped in the opposite direction.
Tanjiro stared.
The stranger was not using a sword.
He was not using a Breathing Style.
He was fighting the Hand Demon with his bare hands.
The Hand Demon swung six arms toward Den.
Den lowered his head.
The first fist passed above him.
He slapped the second one aside.
He caught the third arm beneath his shoulder and used it to block the fourth.
The fifth reached for his waist.
Den stepped onto its wrist.
The sixth arm attempted to crush him from behind.
Den leaned backward without looking.
The fist missed his face by less than an inch.
He caught it with both hands.
Then Den pulled.
The entire demon was dragged forward.
"What?!"
Den drove his knee into the demon's face.
The impact flattened its nose and launched several teeth into the forest.
The Hand Demon stumbled.
Den still held the arm.
He rotated his body and threw the enormous demon over his shoulder.
The creature flew through the air.
It struck the ground with enough force to create a crater.
Tanjiro raised his sword.
"Who are you?"
Den glanced at him.
"Busy."
The Hand Demon roared and forced itself upright.
Its broken arms began regenerating.
Den looked at the regeneration meter above its head.
It rapidly returned to maximum.
**Regenerations Allowed: 1/10**
Den smiled.
"Good. Get up."
The Hand Demon's eyes widened.
It had expected fear.
It had expected anger.
It had expected another swordsman trying desperately to cut through its neck.
It had not expected encouragement.
The demon launched itself at Den.
Twenty arms attacked at the same time.
Den stepped forward.
The forest became filled with impacts.
A fist struck toward Den's chest.
He redirected it into another arm.
A claw approached his throat.
He trapped the wrist beneath his elbow, turned his body, and tore the arm from its socket.
Another hand grabbed his shoulder.
Den caught one finger and performed a joint lock.
The Hand Demon's entire body dropped to one knee.
Den punched it in the throat.
The demon choked.
Den punched it in the stomach.
Its back bent.
Den stepped behind it, wrapped two arms around its waist, lifted the enormous body from the ground, and slammed it backward.
The mountain shook.
The demon regenerated.
**Regenerations Allowed: 2/10**
Den waited.
The Hand Demon screamed and attacked again.
Den kicked one knee sideways.
The leg broke.
He grabbed two arms, crossed them around the demon's neck, and pulled until its own limbs began choking it.
The demon grew three more arms from its back.
Den headbutted it.
Its skull collapsed.
**Regenerations Allowed: 3/10**
Tanjiro stood nearby, uncertain whether he should interfere.
The black-armored stranger was helping him.
Technically.
But there was no kindness in the stranger's movements.
Den was not merely trying to defeat the Hand Demon.
He was studying it.
Every time the demon regenerated, Den used a different method to break its body.
The Hand Demon attempted to retreat.
Den appeared in front of it.
"Where are you going?"
The demon froze.
Den punched its chest.
His fist sank into the creature's body.
He grabbed one of its ribs from the inside.
Then he pulled it out.
The Hand Demon screamed.
Den examined the bone.
"Large."
He struck the demon across the face with its own rib.
**Regenerations Allowed: 4/10**
The demon formed more arms.
Den grabbed one, climbed up the limb, and ran across it.
He jumped from its shoulder.
His heel struck the top of its head.
The creature's face slammed into the dirt.
Den landed on its back.
Two hands attempted to grab him.
He stepped aside.
The demon accidentally grabbed itself.
Den caught both wrists and tied the arms together.
**Regenerations Allowed: 5/10**
The Hand Demon roared.
"Stop moving!"
Den raised one eyebrow.
"You attacked first."
"You appeared in my territory!"
"You were trying to eat him."
Den pointed toward Tanjiro.
The Hand Demon looked at Tanjiro.
Then it looked back at Den.
"That has nothing to do with you!"
"That is true."
Den kicked the demon across the ground.
It smashed through fourteen trees.
"I'm doing this for a mission."
The Hand Demon did not understand what that meant.
Tanjiro did not understand either.
Den walked after it.
The Hand Demon forced its body to regenerate again.
**Regenerations Allowed: 6/10**
It opened its mouth and extended several arms from its throat.
Den watched them approach.
"That is disgusting."
The arms wrapped around his body.
The Hand Demon pulled him into its mouth.
Tanjiro rushed forward.
"Look out!"
The Hand Demon swallowed Den.
Silence followed.
The demon began laughing.
"I ate him!"
Tanjiro tightened his grip around his sword.
The smell had not disappeared.
The Hand Demon's laughter stopped.
A fist struck the inside of its stomach.
Its entire body lifted from the ground.
A second punch struck from within.
The demon's back expanded.
A third impact tore through its chest.
Den stepped out through the opening.
Dark blood covered his armor.
He looked down at himself.
Then he looked at the Hand Demon.
"That was rude."
The demon fell backward.
Its chest regenerated.
**Regenerations Allowed: 7/10**
Den grabbed it by the neck.
He used one hand.
The Hand Demon clawed at his arm.
Den slowly lifted it from the ground.
The demon created more arms and wrapped them around Den's body.
Den tightened his fingers.
The demon's neck compressed.
"Help me!" the Hand Demon screamed.
Tanjiro blinked.
The demon looked at him.
"Human! Help me!"
Tanjiro's expression became completely confused.
The creature that had tried to eat him was now begging him to save it from someone else.
**Bonus Objective Completed**
**Make the boss ask a human for help: Completed.**
Den looked at Tanjiro.
"He asked politely."
Tanjiro raised his sword.
"Put him down."
The Hand Demon stared at Tanjiro hopefully.
Den dropped it.
The Hand Demon landed on its back.
For one second, it looked relieved.
Den stomped on its stomach.
The ground exploded beneath it.
**Regenerations Allowed: 8/10**
Tanjiro moved.
He swung his sword toward Den's shoulder.
Den leaned backward.
The blade passed over his chest.
Tanjiro changed direction immediately.
Den stepped inside the sword's range.
He struck Tanjiro's wrist with two fingers.
Tanjiro's hand opened.
Den caught the sword before it fell.
The entire movement lasted less than a second.
Tanjiro jumped backward.
Den examined the weapon.
A Nichirin sword.
The metal carried energy designed to damage demons.
The sword was not especially powerful compared with Den's equipment, but the construction was interesting.
The Side Mission reacted.
# **Borrowed Sword**
**Living sword owner identified: Tanjiro Kamado.**
**Owner's current physical strength copied as temporary combat limit.**
**Defeat the owner using their own weapon.**
Den rotated the sword.
He changed his grip.
Tanjiro smelled the difference immediately.
Before touching the sword, Den's movements had been powerful and extremely controlled.
Now something had changed.
His stance looked natural.
Too natural.
He held Tanjiro's sword as if he had trained with it for years.
Perfect Sword Comprehension had not been rewarded yet.
But Yin and Yang Combat Skills already gave Den considerable weapon knowledge.
Den pointed the blade toward Tanjiro.
"You told me to put him down."
Behind Den, the Hand Demon regenerated again.
**Regenerations Allowed: 9/10**
Den smiled.
"I did."
The Hand Demon attempted to crawl away.
Den kicked backward.
His heel struck one of its arms without him turning around.
The limb broke.
The demon fell again.
Tanjiro moved forward.
"Give me back my sword!"
"Take it."
Tanjiro reached for the handle.
Den moved the blade.
The flat side struck Tanjiro's fingers.
Tanjiro pulled his hand away.
Den cut downward.
Tanjiro avoided the edge and rolled across the ground.
Den followed.
His physical strength had been reduced to Tanjiro's exact level, but his skill remained far greater.
Tanjiro tried to create distance.
Den refused to allow it.
He attacked with short, controlled cuts that forced Tanjiro backward.
One slash approached Tanjiro's neck.
Tanjiro ducked.
Den rotated the sword and struck him in the stomach with the handle.
Tanjiro lost his breath.
Den swept his legs.
Tanjiro jumped.
Den kicked him while he was still in the air.
Tanjiro flew backward and struck a tree.
His health bar dropped.
### **Tanjiro Kamado**
**Health: 59%**
Tanjiro forced himself upright.
"You're not a Demon Slayer."
"No."
"You're not a demon."
"Also no."
"Then why are you attacking everyone?"
Den thought about it.
"Better rewards."
Tanjiro had absolutely no idea what that meant.
The Hand Demon regenerated completely.
**Regenerations Allowed: 10/10**
**Bonus Objective Completed.**
It stood behind Den.
Every arm pulled backward.
The demon prepared to crush Den and Tanjiro at the same time.
Tanjiro smelled the attack.
"Behind you!"
Den looked at Tanjiro instead of the demon.
"I know."
The Hand Demon attacked.
Den moved Tanjiro's sword behind his back.
He did not turn around.
The blade passed through the space between several incoming arms.
Den changed the angle four times.
The demon's limbs separated from its body.
Dark blood rained through the trees.
Den still had not looked at it.
Tanjiro stared at the fallen arms.
Den finally turned.
The Hand Demon's regeneration had slowed.
Dawn was approaching.
Thin light appeared between the trees.
The demon noticed it.
Fear filled its face.
It attempted to escape again.
Den threw Tanjiro's sword into the ground.
The blade pinned the demon's shadow.
It did not physically touch the Hand Demon.
But Den had calculated the placement.
The creature stepped around the sword.
Den appeared beside it.
He punched one knee.
The leg folded.
The demon fell.
Den grabbed one arm and twisted it behind the creature's back.
The Hand Demon tried to regenerate.
Den broke the new limbs as soon as they appeared.
Sunlight began entering the forest.
"No!" the Hand Demon screamed.
Den forced its face upward.
"You wanted to eat people for forty-seven years."
The demon struggled.
"You killed children."
More sunlight moved across the ground.
"You remembered every person you ate."
The Hand Demon's skin began burning.
Den's white eyes stared directly into its face.
"But you became afraid the second someone treated you like food."
Flames spread across the demon's body.
It screamed.
Den released it only after the sunlight completely surrounded it.
The Hand Demon turned into ash.
Its health bar reached zero.
# **BOSS DEFEATED**
### **Combat Score: SSS**
### **Damage Received: 0**
### **Maximum Combo: 184**
### **Mission Restrictions Maintained**
**Special Mission completed.**
Tanjiro watched the ashes disappear.
The stranger had saved him.
But the smell coming from Den was colder than before.
Den turned toward Tanjiro.
"You are next."
Tanjiro raised his empty hands.
---
### **Sword Owner Versus Sword Thief**
Tanjiro looked at his sword.
It remained embedded in the ground behind Den.
Den stood between him and the weapon.
The Hand Demon had been defeated.
The immediate danger was gone.
But Tanjiro's instincts were screaming louder than they had during the entire battle.
Den was watching his feet.
His breathing.
His shoulders.
His hands.
Every time Tanjiro shifted his weight, Den adjusted before he finished moving.
It felt like fighting someone who already knew what he was about to do.
Tanjiro lowered his body.
Den raised one hand.
"Come take your sword."
Tanjiro charged.
He moved to Den's right.
Den stepped left.
Tanjiro changed direction and aimed a punch toward Den's face.
Den caught the fist.
Tanjiro used the captured arm as support and kicked toward Den's ribs.
Den blocked with his elbow.
Tanjiro landed and attempted a shoulder throw.
Den allowed Tanjiro to begin the movement.
Then he shifted his center of gravity.
Tanjiro tried to pull.
Den did not move.
"Good idea," Den said.
He copied the same throw.
Tanjiro's feet left the ground.
Den slammed him into the dirt.
Tanjiro rolled away before Den could follow.
Den kicked.
Tanjiro blocked with both arms.
The impact pushed him backward.
Den advanced.
Tanjiro threw several fast punches.
Den avoided the first.
Parried the second.
He caught the third, turned Tanjiro's wrist, and forced the arm behind his back.
Tanjiro lowered himself before the joint could break.
He struck Den's knee with his heel.
Den lifted his leg.
Tanjiro escaped.
Den smiled slightly.
Tanjiro was inexperienced, but he adapted quickly.
That made the fight less boring.
Tanjiro rushed toward his sword.
Den followed.
Tanjiro reached the handle.
Den caught the back of his uniform.
Tanjiro pulled the sword free anyway.
He twisted and slashed.
Den released him.
The blade passed across Den's chest.
It created sparks against the Villain Armor but did not leave a mark.
Tanjiro froze for half a second.
Den grabbed the sword with one hand.
He pulled.
Tanjiro held on.
Den headbutted him.
Tanjiro's forehead met Den's.
**BANG!**
The collision shook the nearby trees.
Tanjiro stumbled backward.
Den stared at him.
Tanjiro stared back.
A thin crack appeared in the ground beneath both of them.
Den touched his forehead.
"That was stronger than expected."
Tanjiro's forehead was famous even without a system description.
Den approved.
Tanjiro tightened both hands around the sword.
He controlled his breathing.
His lungs filled.
His body strengthened.
Den saw the muscles adjust.
The oxygen moved through Tanjiro's blood.
The game generated flowing water around the blade as Tanjiro entered a Breathing Style.
Den's smile grew.
"Finally."
Tanjiro attacked.
Water followed the sword.
The blade moved toward Den's neck.
Den leaned aside.
Tanjiro spun and cut upward.
Den stepped back.
The sword passed close to his face.
Tanjiro continued the motion, using the flowing movement of Water Breathing to connect one attack into another.
Den avoided each cut with small movements.
He did not teleport.
He did not use his supernatural speed.
He remained restricted to Tanjiro's physical level.
But his combat skill allowed him to see every opening.
Tanjiro cut horizontally.
Den stepped inside the swing.
He struck Tanjiro's elbow.
The sword changed direction.
Den caught the handle beside Tanjiro's hand.
For one moment, both held the same weapon.
Den twisted.
Tanjiro lost his grip.
Den took the sword again.
# **Borrowed Sword Duel Initiated**
**Host and owner are now equalized in physical strength.**
Den moved before Tanjiro recovered.
The flat side of the blade struck Tanjiro's shoulder.
Then his ribs.
Then his thigh.
Den rotated.
The handle struck Tanjiro's jaw.
Tanjiro blocked the next swing with both forearms.
Den stopped the blade before cutting him.
He turned it and kicked Tanjiro in the chest.
Tanjiro flew through a tree.
The tree broke.
Tanjiro hit the ground.
### **Tanjiro Kamado**
**Health: 31%**
Tanjiro tried to stand.
Den appeared in front of him.
He placed the sword against Tanjiro's neck.
The mission screen appeared.
**The owner has been defeated using their own weapon.**
**Owner remains alive.**
# **Side Mission Completed**
### **Rewards Acquired**
* Perfect Sword Comprehension
* Weapon Theft Mastery
* Permanent upgrade option unlocked for stolen sword
Information entered Den's mind.
His understanding of swords changed instantly.
Before, he had possessed advanced combat knowledge.
Now every part of the weapon became completely familiar.
Weight.
Balance.
Edge alignment.
Metal quality.
Grip pressure.
Distance.
Timing.
A sword was no longer an object in his hand.
It became an extension of his body.
Den removed the blade from Tanjiro's neck.
Tanjiro breathed heavily.
"Why didn't you kill me?"
Den looked at him.
"Because you lost."
"That doesn't answer my question."
"It does to me."
Den stepped back.
Tanjiro remained on the ground.
Den raised the sword.
Darkness flowed across its metal.
The system opened an upgrade menu.
### **Stolen Nichirin Sword Upgrade Available**
**Current Owner: Den**
**Previous Owner: Tanjiro Kamado**
**Select Upgrade Path**
1. **Dark Nichirin**
2. **Demon-Eating Blade**
3. **Nightmare Weapon**
4. **Blood-Drinking Sword**
5. **Random Mutation**
Den selected the fifth option.
Tanjiro stared at him.
"You don't know what that will do."
Den glanced at him.
"That is why I picked it."
**Upgrade selected: Random Mutation.**
The sword began shaking.
Its metal turned black.
Then red.
Then white.
The blade bent sideways.
An eye opened near the handle.
The eye looked at Den.
Den looked at the eye.
The sword grew teeth.
Tanjiro looked horrified.
Den remained silent.
The weapon attempted to bite his hand.
Den caught the blade with his other hand and squeezed.
The eye widened.
"Behave."
The sword stopped moving.
The teeth disappeared.
The eye closed.
The blade became straight again.
### **Weapon Mutation Completed**
# **Living Nightmare Nichirin**
* Can damage humans, demons, spirits and artificial entities.
* Regenerates from damage.
* May consume the blood of defeated opponents to improve itself.
* Possesses limited intelligence.
* May occasionally attempt to bite an unworthy user.
* Is currently terrified of Den.
Den rotated the sword.
"Good choice."
Tanjiro did not agree.
A wooden box rested nearby.
Den had noticed it during the battle.
His enhanced senses detected a demon sleeping inside.
Tanjiro followed Den's gaze.
He immediately moved between Den and the box.
"Stay away from her."
Den looked at Tanjiro.
The boy was injured.
His health had fallen below one-third.
He had no weapon.
Yet he still stood between Den and the demon inside the box.
Den could smell fear coming from him.
Not fear for himself.
Fear for someone else.
The mission requested that Den terrify Tanjiro without threatening his sister.
He could complete that.
Den walked toward Tanjiro.
Tanjiro raised his fists.
Den stopped directly in front of him.
"I'm not going to kill your sister."
Tanjiro did not relax.
"You knew she was inside?"
"I can see through the box."
Tanjiro's expression changed.
Den continued.
"I could have killed her while you were fighting the Hand Demon."
Tanjiro's hands tightened.
"I could have destroyed the entire mountain before you noticed me."
Den leaned slightly closer.
"I could kill every human and demon in this universe."
Tanjiro's breathing became uneven.
"But I'm not going to touch her."
"Why?"
Den's white eyes narrowed.
"Because watching you wonder why is funnier."
Tanjiro smelled no lie.
That made the answer worse.
Den stepped past him.
Tanjiro turned.
"What are you?"
Den considered the question.
The Villain Halo floated behind him.
The Living Nightmare Nichirin rested against his shoulder.
The ashes of the Hand Demon disappeared into the morning wind.
"I'm the person both sides are going to blame."
Tanjiro stared at him.
His expression hardened.
"You're worse than a normal demon."
The system reacted immediately.
# **Hidden Villain Mission Completed**
**Tanjiro Kamado has personally identified the host as a greater threat than an ordinary demon.**
### **Bonus Objectives Completed**
* Terrified Tanjiro without threatening his sister.
* Defeated Tanjiro through hand-to-hand combat.
* Defeated Tanjiro through sword combat.
* Left Tanjiro alive for reasons other than mercy.
### **Bonus Objective Remaining**
* Demonstrate demon-style combat ability.
### **Partial Rewards Distributed**
* Villain Presence upgraded by 300%.
* Fear Absorber upgraded.
* Future Tanjiro mission unlocked.
Den stopped walking.
One objective remained.
He looked toward the deeper forest.
Several demons were approaching.
They had smelled blood.
Den smiled.
"Watch carefully."
---
### **Learning How Demons Fight**
Six demons emerged from between the trees.
One crawled on four limbs.
Another had two mouths.
The largest carried a broken sword.
The others possessed claws, hardened skin, or extended tongues.
They saw Tanjiro first.
Then they noticed Den.
Every demon stopped.
They could not identify him.
He looked similar to a demon.
He smelled nothing like Muzan.
Sunlight touched his armor without damaging him.
The broken halo behind his head made their instincts scream.
One demon pointed toward him.
"What are you?"
Den lifted the Living Nightmare Nichirin.
"I was just asked that."
The sword opened its eye.
The demons stepped backward.
**Ding!**
**Special Mission rewards are being distributed.**
### **Perk Acquired: Demon Combat Instinct**
Den's posture changed.
Demon Combat Instinct did not teach normal martial arts.
It taught him how a demon's body could be used without human limitations.
A human protected their joints.
A demon could deliberately dislocate them to attack from impossible directions.
A human avoided deep wounds.
A demon could allow an opponent to stab them, trap the weapon inside their body, regenerate around it, and counterattack.
A human possessed a fixed body structure.
A demon treated its muscles, bones, skin and blood as weapons.
Den did not possess a normal demon's regeneration weakness.
Nightmare Mode already regenerated his body.
Super Defense made damaging him nearly impossible.
Now he understood how to combine that body with the most brutal habits of demon combat.
Another reward appeared.
### **Ability Acquired: Bloodless Demon Art Creation**
**The host may create Demon Arts without consuming human blood or receiving blood from a demon progenitor.**
**Created arts will use darkness, stamina, fear or other available energies instead of blood.**
**The host is not given a sunlight weakness.**
**The host remains independent from all demon bloodlines.**
Den raised his free hand.
Darkness gathered around his fingers.
His body reacted.
The black material covering his arm changed.
His fingernails extended into claws.
A second joint formed in each finger.
The arm stretched slightly.
White markings moved from his shoulder toward his hand.
A name entered his mind.
# **Bloodless Demon Art: Predatory Black Body**
Den could alter parts of his body for combat.
Claws.
Blades.
Extra joints.
Hardened bones.
Extended limbs.
Additional eyes.
Reinforced muscles.
Temporary mouths.
He could create what he needed without permanently changing his human shape.
The crawling demon attacked first.
It moved low to the ground and aimed for Den's legs.
Den bent backward.
His spine moved farther than a human spine should.
The demon passed beneath him.
Den's leg twisted completely around.
His heel struck the demon in the back of the head.
Its face slammed into the ground.
Before it recovered, Den's arm extended.
His claws grabbed its ankle.
He pulled.
The demon flew backward.
Den spun it around his body and used it to strike two other demons.
All three crashed through the forest.
Tanjiro watched in horror.
Den's movements no longer resembled human martial arts.
They were too loose.
Too violent.
Too willing to use unnatural angles.
The largest demon raised the broken sword and charged.
Den blocked with the Living Nightmare Nichirin.
The blades collided.
Den released his sword.
The demon was surprised.
Den allowed the broken blade to enter his shoulder.
Tanjiro's eyes widened.
Den caught the demon's wrist.
Darkness regenerated around the weapon, trapping it inside his body.
The demon pulled.
The sword did not move.
Den smiled.
"Mine."
He headbutted the demon.
Its skull cracked.
Den pulled the broken sword from his shoulder and stabbed it through the demon's mouth.
His injury closed immediately.
The two-mouthed demon attacked from behind.
Both mouths opened.
Long tongues wrapped around Den's arms.
Den dropped the broken weapon.
His shoulders dislocated.
His arms rotated backward.
He grabbed both tongues.
The demon froze.
Den pulled it toward him.
He drove both knees into its faces.
Teeth flew through the air.
Den landed.
His shoulders returned to normal.
The remaining demons attempted to surround him.
Den used the Living Nightmare Nichirin.
Perfect Sword Comprehension controlled every movement.
The blade moved once.
A black line appeared through the forest.
Three demons lost their arms.
Den reversed the grip.
The sword passed behind his back.
A demon approaching from his blind spot lost both legs.
Den stepped forward.
# **Nightmare Sword Art**
## **First Form: Black Star Draw**
Den disappeared.
The sound of the sword leaving its position came after the attack was already completed.
He reappeared behind the demons.
A circular cut passed through their bodies.
All six demons were divided at the waist.
Their upper bodies struck the ground.
They began regenerating.
Den looked at the Living Nightmare Nichirin.
The sword's eye opened.
Its teeth returned.
"Hungry?"
The sword shook excitedly.
Den released it.
The weapon floated into the air.
It flew toward the wounded demons.
The demons screamed.
The sword moved between them, biting into their bodies and consuming their blood.
Tanjiro stared.
Den watched calmly.
One demon attempted to crawl away.
Den stepped on its back.
The demon looked up at him.
"What do you want?"
"A messenger."
The demon's face changed.
Den's Darkness Mind Control entered its shadow.
The creature struggled.
It possessed cruelty, hunger, hatred, and countless murders inside its mind.
There was more than enough darkness for Den to control.
The demon stopped moving.
Its eyes turned black.
Den released his foot.
"Go to the person whose blood is inside you."
The demon trembled.
It understood exactly who Den meant.
"Tell Muzan Kibutsuji something."
Tanjiro reacted to the name.
The controlled demon lowered its head.
Den smiled.
"Tell him I entered his world without permission."
The demon waited.
"And tell him I'm not asking for it."
The darkness released the creature.
It jumped to its feet and fled through the forest.
Tanjiro looked at Den.
"You let it escape!"
"Yes."
"It will kill more people!"
Den glanced toward the fleeing demon.
"No."
Far away, the demon reached the edge of the forest.
Its body suddenly separated into small black pieces.
The pieces transformed into crows.
The crows continued flying in different directions.
Tanjiro stared.
Den had turned the demon into a message.
Not sent it to deliver one.
A black symbol appeared across every crow's chest.
It resembled Den's broken halo.
The crows would seek other demons.
Every demon that touched them would receive the message directly inside its mind.
Muzan would eventually hear it through his blood connection.
Den looked at Tanjiro again.
"I said I needed a messenger. I didn't say it needed to remain alive."
The system reacted.
# **Bad First Impression**
**Final bonus objective completed.**
**Demonstrated demon-style combat ability.**
### **Full Completion Reward**
* Fear Absorber upgraded to **Terror Devourer**
* Villain Presence upgraded to **Calamity Presence**
* Future mission unlocked: **Break the Unbreakable Kindness**
Tanjiro felt pressure spread from Den.
The birds stopped making noise.
The remaining demons on the mountain changed direction and ran.
Several candidates dropped their weapons without understanding why.
Den's upgraded presence did not force fear into people.
It made them understand that they were near something capable of causing disaster.
Den looked toward the rest of Final Selection.
"There are more demons."
Tanjiro stepped in front of him.
"You can't keep doing this."
Den stopped.
"Doing what?"
"Treating everyone like they're part of a game!"
Den looked at the floating health bar above Tanjiro's head.
A small tutorial symbol appeared beside it.
Den almost laughed.
"You are not going to believe the answer."
A crow cried from the sky.
Then another presence entered Den's senses.
Fast.
Controlled.
Cold.
A swordsman was approaching.
Tanjiro recognized the scent.
Den recognized the name floating between the trees.
### **Giyu Tomioka**
**Water Hashira**
**Current Objective: Investigate abnormal activity**
**Threat Assessment of Host: Unknown**
Den's smile slowly widened.
"One Hashira."
---
### **The Water Hashira Arrives**
Giyu appeared between Den and Tanjiro.
His sword was already drawn.
He looked at Tanjiro's injuries.
Then at the Living Nightmare Nichirin.
Then at Den.
Giyu's expression remained calm, but his grip tightened.
He had seen the damage across the forest.
He had smelled demons burning in sunlight.
He had followed the unnatural pressure spreading from Final Selection.
He expected a powerful demon.
Instead, he found something standing in sunlight while carrying Tanjiro's sword.
"Move away from him," Giyu said.
Den looked behind himself.
There was no one there.
"You mean me?"
Giyu did not answer.
Tanjiro struggled to remain standing.
"He's not a demon!"
Giyu's eyes stayed on Den.
"I know."
"He attacked the Hand Demon, but then he attacked me, and he can use something like a Blood Demon Art, but he doesn't smell like Muzan, and his sword tried to eat someone—"
Giyu briefly looked at Tanjiro.
Tanjiro stopped speaking.
Den nodded.
"Very clear explanation."
Giyu raised his sword.
"Return the weapon."
The Living Nightmare Nichirin opened its eye.
It looked at Giyu.
Then it looked at Den.
The weapon moved closer to Den as if hiding.
Den rested it against his shoulder.
"It likes me more."
"That isn't your sword."
"It attempted to bite me. We bonded."
Giyu stepped forward.
The air changed around him.
His breathing became controlled.
Water formed around his blade.
Den's Mission Tab opened.
# **Hashira Challenge Detected**
### **Special Combat Mission: Three Ways to Lose**
**Defeat a Hashira using three separate combat systems.**
1. Hand-to-hand combat
2. Sword combat
3. Demon-style combat
### **Restrictions**
* The host must reduce physical ability to the Hashira's approximate level.
* No teleportation.
* No direct dark magic attacks.
* No Darkness Clones.
* No attack may destroy more than one kilometer of the surrounding area.
* The Hashira must remain alive until all three combat phases are completed.
### **Bonus Objectives**
* Force the Hashira to retreat at least once.
* Take the Hashira's sword without breaking it.
* Make the Hashira show visible surprise.
* Win the final exchange without holding a weapon.
* Leave the Hashira alive because the host wants a rematch.
### **Rewards**
* High-Level Combat Trait
* One original sword style
* One original Demon Art
* Immediate progress toward Main Mission 2
* Hashira combat data stored permanently
Den read the restrictions.
He looked at Giyu.
"Good news."
Giyu remained silent.
"I'm not allowed to kill you yet."
Tanjiro's face dropped.
That was not good news.
Den pushed the Living Nightmare Nichirin into the ground.
He raised both empty hands.
"First round."
Giyu attacked.
His sword crossed the distance instantly.
Den tilted his head.
The blade passed beside his cheek.
Den stepped into Giyu's range and punched toward his ribs.
Giyu lowered his elbow.
The punch was blocked.
Den opened his fist and caught Giyu's sleeve.
Giyu rotated the sword.
Den released him and leaned away.
The blade cut through the edge of Den's uniform but failed to touch his armor.
Giyu continued attacking.
Water flowed around the sword.
Each slash connected smoothly into the next.
Den avoided them by moving around Giyu instead of retreating.
He stepped beside the blade.
Behind the handle.
Around Giyu's shoulder.
Giyu turned.
Den struck his wrist.
Giyu kept hold of the sword.
Den kicked toward his knee.
Giyu jumped.
Den caught his ankle.
He pulled Giyu from the air.
Giyu twisted his body and swung downward.
Den released the leg.
The sword cut through the ground.
Den stepped onto the flat side of the blade.
Giyu attempted to pull it free.
Den kicked him in the chest.
Giyu slid backward.
His feet carved two lines through the dirt.
His expression changed slightly.
Not fear.
Not yet.
But surprise.
**Bonus Objective Completed**
**Make the Hashira show visible surprise.**
Den moved first.
He rushed toward Giyu with normal physical speed equal to the Hashira's level.
Giyu cut horizontally.
Den dropped beneath the blade.
He planted both hands against the ground.
His legs rotated.
One heel struck Giyu's sword hand.
The other aimed for his head.
Giyu blocked with his forearm.
Den's kick pushed him sideways.
Den landed and attacked with an elbow.
Giyu moved his head.
The elbow passed close to his face.
Giyu struck Den's stomach with the handle of his sword.
Den accepted the impact.
He trapped Giyu's arm beneath his elbow.
The sword became stuck between them.
Den drove his forehead into Giyu's face.
Giyu stepped backward.
Den followed with a knee.
Giyu blocked.
Den changed direction in the middle of the movement.
His foot struck Giyu's thigh.
Giyu's leg weakened.
Den hooked it.
The Water Hashira fell.
Before Giyu touched the ground, Den caught his uniform and threw him into a tree.
Giyu rotated in the air and landed feet-first against the trunk.
He pushed away from it.
His sword aimed directly at Den's neck.
Den raised one hand.
The blade stopped between his palms.
Giyu's eyes narrowed.
Den twisted.
The sword was pulled from Giyu's hands.
**Bonus Objective Completed**
**Take the Hashira's sword without breaking it.**
Den threw the weapon behind himself.
It landed beside Tanjiro.
Giyu immediately attacked without it.
His fist struck toward Den's chest.
Den blocked.
Giyu followed with a palm strike.
Den redirected it.
Giyu attempted to grab Den's arm.
Den allowed him.
Giyu turned his body and threw Den over his shoulder.
Den struck the ground.
Giyu moved to pin him.
Den's spine bent backward unnaturally.
His legs wrapped around Giyu's neck.
Den pulled him down.
Giyu struck the dirt.
Den rolled over him, trapped one arm, and pressed a knee against his shoulder.
Giyu attempted to rise.
Den increased the pressure.
The ground cracked beneath Giyu.
"First loss," Den said.
Giyu twisted his arm and escaped before the shoulder broke.
He rolled toward his sword.
Tanjiro grabbed it and threw it.
Giyu caught the handle.
Den allowed him to recover.
**Hand-to-Hand Phase Completed.**
Giyu returned to his stance.
Den walked toward the Living Nightmare Nichirin.
He pulled it from the ground.
The sword opened its eye.
"Second round."
Giyu attacked again.
Their blades collided.
The forest filled with metal impacts.
Giyu's swordsmanship was controlled, efficient and direct.
Den's was completely different.
Perfect Sword Comprehension combined every style he understood.
He used normal slashes.
Reverse-grip cuts.
One-handed thrusts.
Half-sword techniques.
He moved the blade behind his back, beneath his arms, and around his own body without losing control.
Giyu cut toward Den's shoulder.
Den blocked with the center of his blade.
He allowed Giyu's sword to slide downward.
Then he trapped it against the Living Nightmare Nichirin's guard.
Den rotated.
Giyu's weapon was redirected into a tree.
Den slashed toward Giyu's side.
Giyu pulled away.
The blade cut his uniform.
A thin line appeared across his skin.
Giyu's health bar decreased slightly.
Den saw the change.
"Your health bar moved."
Giyu did not know what that meant.
Den attacked again.
# **Nightmare Sword Art**
## **Second Form: Funeral Orbit**
Den spun the sword around his body.
The blade created a circle of black cuts.
Giyu blocked the first.
Avoided the second.
Redirected the third.
The fourth came from beneath him.
Giyu jumped.
Den followed him into the air.
Their swords collided seven times before either landed.
Giyu touched the ground first.
Den landed on the flat side of Giyu's sword.
Giyu looked up.
Den kicked him in the face.
Giyu flew backward.
He struck several trees but cut through them before they could trap him.
Den followed.
Giyu controlled his breathing.
The water surrounding his sword became calmer.
His presence became still.
Den's sword attacked.
Giyu moved once.
The strike disappeared.
Den's next cut was stopped.
Then another.
The flowing defense removed the force behind every attack.
Den recognized the technique.
A defensive form designed to reduce incoming attacks to nothing.
Den increased his sword speed.
Ten cuts.
Twenty.
Fifty.
Giyu's blade moved around him.
Every strike was intercepted.
The game's visual effects created a silent area of water.
Den's smile widened.
He did not increase his strength.
He changed his rhythm.
His first attack was fast.
The second was slower.
The third stopped before reaching Giyu.
The fourth came from an unusual angle.
The fifth was not aimed at Giyu at all.
Den struck the ground.
Dirt rose between them.
Giyu's vision was blocked for half a second.
Den threw his sword.
The Living Nightmare Nichirin flew past Giyu's shoulder.
Giyu turned toward it.
Den followed the weapon.
He grabbed the handle while it was behind Giyu and cut backward.
Giyu barely blocked.
The defensive rhythm broke.
Den struck again.
Giyu was forced to move backward.
One step.
Three steps.
Ten steps.
Den continued attacking.
Giyu retreated from the forest clearing.
**Bonus Objective Completed**
**Force the Hashira to retreat at least once.**
Den moved the sword into his left hand.
His right fist struck Giyu's sword.
The weapon moved aside.
Den's blade stopped against Giyu's throat.
"Second loss."
Giyu remained still.
A thin line of blood appeared beneath the edge.
Den removed the sword.
Giyu stepped away.
**Sword Combat Phase Completed.**
Tanjiro watched from beside the trees.
Den had defeated Giyu twice.
But Den's smell had changed again.
The black markings around his arms were moving.
His fingers extended into claws.
The Living Nightmare Nichirin returned to its sheath of darkness.
Den's shoulders dislocated slightly.
His arms hung at unnatural angles.
Then they corrected themselves.
White lines spread across his chest.
Four additional eyes opened along his forearms.
Giyu's expression became colder.
"Demon Art."
"Bloodless," Den corrected.
He lowered himself onto all fours.
Giyu tightened his grip around his sword.
"Third round."
Den moved.
His body crossed the ground like a predator.
Giyu slashed downward.
Den's shoulder collapsed inward.
The blade passed through the space where the joint had been.
Den's arm stretched around Giyu's waist.
He pulled himself closer.
His knee struck Giyu's stomach.
Giyu was launched upward.
Den followed.
His claws cut toward Giyu's chest.
Giyu blocked.
Den's second arm bent around the sword.
His elbow formed an extra joint.
The claw approached Giyu from behind.
Giyu twisted in the air.
The attack cut part of his haori.
Both landed.
Den immediately attacked again.
His body movements were impossible to predict through normal sword training.
A punch could become a claw strike.
A missed kick could bend backward and attack again.
His arms could lengthen.
His joints could reverse.
Giyu cut through Den's forearm.
The blade entered the darkness covering his body.
Den did not pull away.
He smiled.
The wound closed around Giyu's sword.
The weapon became trapped.
Giyu attempted to remove it.
Den punched him in the chest.
The impact threw Giyu backward, but the sword remained inside Den's arm.
Den pulled it free.
He examined the blade.
"Sharp."
Giyu landed and looked at his empty hand.
Den tossed the sword toward him.
Giyu caught it.
"You gave it back."
"You need it."
Den's arms returned to normal.
Then darkness gathered behind him.
Not clones.
The mission prohibited Darkness Clones.
Instead, the darkness formed delayed copies of Den's previous movements.
# **Bloodless Demon Art**
## **Predatory Black Body: Murder Echo**
Den punched.
Giyu avoided the fist.
One second later, a dark copy of the same punch appeared from the original position.
Giyu blocked it.
Den kicked.
Giyu jumped over the attack.
A delayed black kick followed him into the air.
It struck his side.
Giyu was thrown across the clearing.
Den rushed forward.
He attacked with his elbow.
Then his knee.
Then both claws.
Every missed strike remained behind as a Murder Echo.
Giyu was no longer fighting one series of attacks.
He was fighting the current Den and the delayed remains of everything Den had already done.
The Water Hashira blocked a claw.
A previous punch struck his shoulder.
He avoided a kick.
A delayed elbow struck his ribs.
He cut toward Den.
Den opened his hand and caught the sword.
A Murder Echo appeared behind Giyu.
The dark fist stopped beside his head.
Giyu froze.
Den released the blade.
He stepped forward.
His forehead struck Giyu's forehead.
Giyu stumbled.
Den swept his legs.
Giyu fell.
Den dropped the Living Nightmare Nichirin several meters away.
He held no weapon.
Giyu tried to rise.
Den's hand stopped against his throat.
The claws rested against his skin.
The Murder Echo behind him remained beside his skull.
Either attack could end the fight.
"Third loss."
Silence covered the forest.
# **Hashira Challenge Completed**
### **All Three Combat Phases Completed**
* Hand-to-hand combat victory
* Sword combat victory
* Demon-style combat victory
### **Bonus Objectives**
* Forced Hashira retreat: Completed
* Took Hashira's sword without breaking it: Completed
* Created visible surprise: Completed
* Won final exchange without holding a weapon: Completed
* Leave Hashira alive for desired rematch: Pending
Den looked down at Giyu.
The claws could enter his throat immediately.
Giyu did not beg.
He did not look away.
His breathing remained controlled despite his injuries.
Den liked that.
He removed his hand.
Giyu's expression changed slightly.
"Why?"
Den's claws shortened.
"You have better technique than everyone else I met today."
"That isn't an answer."
"I want to fight you again after you become stronger."
Den turned away.
"Killing you now would ruin the rematch."
**Final Bonus Objective Completed.**
### **Perfect Mission Completion**
Giyu pushed himself upright.
"You will regret leaving me alive."
Den glanced over his shoulder.
"That is the correct response."
---
### **The Villain Improvement**
The rewards entered Den's body.
**Ding!**
### **High-Level Combat Trait Acquired**
# **Unpredictable Battle Tyrant**
* Every successful change in combat style temporarily increases speed and attack power.
* Repeating the same combination gradually weakens its effectiveness.
* Unexpected attacks gain increased accuracy.
* Opponents have greater difficulty reading the host's intentions.
* The host's battle instincts become more dangerous as the fight continues.
* Improvised weapons receive temporary mastery.
* Cruel or confusing tactical choices may produce additional fear.
Den immediately understood how the trait worked.
It encouraged him not to fight the same way twice.
A punch followed by another punch was ordinary.
A punch followed by a sword throw, a dislocated shoulder, a shadow bite, and using the opponent's shoe as a weapon was harder to predict.
Den looked at Giyu's footwear.
Giyu moved one foot backward.
Den smiled.
The system continued.
### **Original Sword Style Created**
# **Nightmare Breathing**
**Nightmare Breathing does not require normal oxygen-based enhancement.**
**It uses controlled fear, darkness, killing intent and physical rhythm to imitate and surpass the effects of Breathing Styles.**
### **Current Forms**
1. **Black Star Draw**
2. **Funeral Orbit**
3. **Dead Angle Feast**
4. **Broken Moon Reversal**
5. **No-Witness Execution**
Den tested the breathing method.
He inhaled.
Fear from across the mountain entered his lungs.
Darkness moved through his body.
The world became clearer.
His sword vibrated.
Unlike normal Breathing Styles, Nightmare Breathing became more powerful when enemies feared him.
The system continued again.
### **Original Demon Art Created**
# **Bloodless Demon Art: Violence Without Shape**
Den could now temporarily alter the physical rules of his attacks.
A fist did not always need to behave like a fist.
A sword cut could strike like a hammer.
A kick could pierce.
A claw could create blunt force.
A blocked attack could become sharp after touching the defense.
The ability made predicting damage nearly impossible.
An opponent might block Den's punch expecting impact, only for the punch to cut through the guard.
They might dodge a sword's edge and be crushed by the air around its flat side.
Den looked at his hand.
"That is unfair."
**Ding!**
**The host is currently following the Villain Route.**
"Right."
The Main Mission updated.
# **Main Mission 2: Enemy of Everyone**
* Defeat 20 Demon Slayers: **2/20**
* Defeat 100 Demons: **7/100**
* Defeat one Hashira: **1/1**
* Make a member of the Twelve Kizuki fear the host: **0/1**
* Receive official kill-on-sight orders: **0/2**
Den looked at the Demon Slayer count.
"Only two?"
He looked around.
Other Final Selection candidates were hiding throughout the forest.
Giyu realized where Den was looking.
"Don't."
Den disappeared.
The teleportation restriction had ended.
He reappeared behind a candidate several kilometers away.
The candidate turned.
Den tapped the side of his head.
The candidate spun through the air and landed unconscious inside a bush.
**Demon Slayers defeated: 3/20**
Den vanished again.
He appeared before two candidates fighting a demon.
Den punched the demon.
Its head separated from its shoulders.
He kicked the first candidate into a tree.
He took the second candidate's sword and struck them with the flat side.
Both fell unconscious.
**Demon Slayers defeated: 5/20**
**Demons defeated: 8/100**
Den continued.
He did not kill every candidate.
That would have been predictable.
One candidate attacked him without warning.
Den broke the sword and threw the person into a lake.
Another candidate surrendered immediately.
Den gave her directions toward the safest path out of the forest.
A third attempted to stab Den while he was helping them.
Den buried the person upside down with only their legs above the dirt.
A fourth insulted his halo.
Den threw him through nine trees.
A fifth complimented the armor.
Den left him alone.
A sixth asked whether Den was a demon.
Den said no.
The candidate asked whether he was sure.
Den punched him.
Within several minutes, twenty Demon Slayers had been defeated.
Most remained alive.
A few who continued attacking after witnessing the difference in strength were not as fortunate.
Den used different methods every time.
He defeated one with a shoulder throw.
One with a sword handle.
One with a tree branch.
One with their own shoe.
One with a demon's severed arm.
The shoe had been surprisingly effective.
**Objective Completed: Defeat 20 Demon Slayers.**
Den then hunted the demons.
He restricted himself again.
Using full power would have destroyed the mountain and completed nothing useful.
He wanted combat experience.
He moved through the forest with the Living Nightmare Nichirin.
The first demon lost its head to **Black Star Draw**.
The second attacked from above.
Den caught it and used **Violence Without Shape**, turning a normal throw into a cutting attack.
The demon was divided when it struck the ground.
The third possessed hardened skin.
Den punched it.
The punch transformed into a piercing attack after contact.
His fist passed through the demon's chest.
The fourth created poisonous claws.
Den allowed one to scratch his armor.
The poison entered the darkness and disappeared.
Den took the demon's claws and attached them temporarily to his own fingers.
He killed the demon with its own poison.
The fifth demon tried to hide among human bodies.
Den saw its health bar.
"That is cheating badly."
He kicked its head from its shoulders.
The combo counter increased.
### **COMBO: 72**
Den moved faster.
He fought with his sword.
His fists.
His elbows.
His knees.
Claws.
Broken weapons.
Rocks.
Tree branches.
One demon was beaten to death with another demon.
One was thrown beyond the invisible game boundary.
A warning appeared.
### **OUT OF BOUNDS**
The demon struck the barrier.
Den followed.
He punched the invisible wall.
It cracked.
The demon looked behind itself.
Then at Den.
"No."
Den punched again.
The game boundary shattered.
The demon fell out of the map.
It disappeared into an unfinished white emptiness beneath the mountain.
**Demons defeated: 61/100**
**Game boundary destroyed: 1**
**Minor Reward: Map-Breaking Talent acquired.**
Den looked into the unfinished area.
Several trees had no backs.
A mountain floated without a bottom.
An untextured crow stood in the emptiness.
The crow looked at Den.
Den looked at the crow.
The crow slowly walked behind a floating rock.
Den repaired the boundary with darkness and returned to the forest.
By sunrise, one hundred demons had been defeated.
The final demon was small and thin.
It dropped to its knees before Den.
"Please!"
Den stopped.
The demon trembled.
"I surrender!"
Den considered killing it.
That was expected.
He considered sparing it.
Also expected after the surrender.
Den thought of a third option.
He handed the demon the Living Nightmare Nichirin.
The sword opened its eye.
The demon stared at it.
Den pointed toward another demon hiding behind a tree.
"Kill that one."
The surrendered demon held the sword with shaking hands.
The hiding demon ran.
The sword pulled its new temporary holder after it.
Both disappeared into the forest.
Several seconds later, screaming echoed across the mountain.
The Living Nightmare Nichirin returned by itself.
The blade was covered in blood.
The surrendered demon did not return.
Den accepted the sword.
"Good job."
The weapon moved happily.
**Demons defeated: 100/100**
---
### **Both Sides Notice Him**
Far away from Final Selection, a man standing inside a dark room suddenly stopped walking.
Muzan Kibutsuji felt demons disappearing.
Not one.
Not ten.
Dozens.
Then more.
Their deaths were too fast.
Some had been killed by Nichirin steel.
Some by sunlight.
Others had been destroyed through methods Muzan could not immediately understand.
One had fallen outside the boundaries of the world itself.
Muzan accessed the blood memories of the remaining demons.
He saw a black figure.
White eyes.
A broken halo.
A sword with teeth.
Then black crows carrying a message entered the minds of demons across the region.
The message reached Muzan.
A voice spoke directly through his blood.
**I entered your world without permission.**
Muzan's expression changed.
The crows continued.
**I'm not asking for it.**
Darkness moved through the blood connection.
For one instant, Muzan felt something looking back at him.
Den saw him.
Across an impossible distance, Den's white eyes appeared inside every drop of demon blood connected to Muzan.
Muzan severed the connection.
The room around him cracked.
He did not understand what Den was.
Den was not one of his demons.
Den was not affected by his blood.
Den stood in sunlight.
Den controlled demons through a different power.
Worst of all, Den had used Muzan's own connection to look back at him.
For the first time in many years, Muzan felt a small amount of fear.
The feeling lasted less than one second.
That was enough.
**Ding!**
**A member connected to the Twelve Kizuki system has feared the host through their progenitor network.**
**Objective progress condition partially exceeded.**
**Special target detected: Muzan Kibutsuji.**
**Fear confirmed.**
# **Objective Completed**
**Make a member of the Twelve Kizuki fear the host: 1/1**
Den stood on the mountain.
He smiled.
"Found you."
A crow belonging to the Demon Slayer Corps flew above Final Selection.
It had witnessed the destruction.
It had seen Giyu defeated.
It had recorded Den attacking candidates and demons without choosing a side.
The crow flew toward Demon Slayer headquarters.
Giyu watched it leave.
Tanjiro stood beside him, holding his injured arm.
"What happens now?" Tanjiro asked.
Giyu stared toward Den.
"We warn everyone."
Den heard him from several kilometers away.
His smile grew.
Soon, the Demon Slayer Corps would issue an order against him.
Muzan would do the same.
Both sides would hunt him.
Den hoped they sent their strongest people first.
The Mission Tab opened again.
# **New Missions Available**
## **Main Mission 3: The King Is Not Invited**
**Find Muzan Kibutsuji and force him to acknowledge that the host stands above his authority.**
### **Objectives**
* Defeat three Upper Rank demons.
* Survive one complete Infinity Castle ambush without destroying the castle.
* Steal control of one room from Nakime.
* Resist Muzan's blood and curse.
* Force Muzan to kneel, retreat or ask for assistance.
* Choose whether to kill, enslave or release Muzan afterward.
### **Rewards**
* High-Level Perk: **Demon King Devourer**
* Immunity to biological corruption
* Infinity Castle ownership token
* One legendary villain weapon
* Ten random perks
---
## **Special Mission: Hashira Collection**
**Defeat every active Hashira through a different primary combat method.**
### **Current Progress: 1/9**
**Giyu Tomioka — Hand-to-hand, sword and Demon Art combination**
### **Rewards**
* Hashira-level sword talent converted into permanent attributes.
* Nine unique combat perks.
* Special title: **The Tenth Disaster**
* Unlock Hashira Nightmare Forms.
---
## **Hidden Mission: Break the Unbreakable Kindness**
**Make Tanjiro Kamado genuinely desire to kill the host.**
### **Restrictions**
* Do not control Tanjiro's mind.
* Do not kill Nezuko.
* Do not permanently remove Tanjiro's emotions.
* Tanjiro must reach the decision through his own judgment.
### **Reward**
* Unknown.
Den read the hidden mission twice.
He looked toward Tanjiro.
Tanjiro felt his attention and immediately moved closer to Nezuko's box.
Den smiled.
"That one might take some work."
The ground beneath Den suddenly changed.
A wooden door appeared under his feet.
The door opened.
An enormous room waited below.
Staircases crossed in impossible directions.
Platforms floated through open space.
Walls moved.
The sound of a biwa echoed from somewhere deep inside.
Nakime had opened a path to the Infinity Castle.
Muzan had not waited for Den to find him.
He had attempted to pull Den into an ambush.
Giyu rushed forward.
"Move!"
Den remained standing above the opening.
The floor disappeared beneath him.
He began falling into the Infinity Castle.
He could have teleported away.
He could have destroyed the castle.
He could have refused.
Instead, Den crossed his arms and allowed himself to fall.
The Living Nightmare Nichirin opened its eye excitedly.
Den looked down at the endless rooms beneath him.
Demons were gathering.
Several powerful presences waited in the darkness.
Den's Villain Halo expanded.
His Calamity Presence entered the castle before the rest of him.
The biwa music stopped for half a second.
Den smiled.
"Finally."
The doors closed above him.
"Customer service."