Arthur hadn't expected any ordinary enemy to force him to take things seriously so soon.
More importantly, this was the first time since awakening his powers that an opponent had met his full physical strength head-on and wasn't repelled.
That realization lingered unpleasantly in his mind as he stood alone in the cavern.
"So this is what 'scaled to the host's strength' really means…" he muttered.
The system hadn't exaggerated.
For a fleeting moment, Arthur considered activating the Boosted Gear. The thought came naturally, almost instinctively, but he pushed it aside just as quickly.
The system's words echoed in his mind again.
The purpose of this place is training.
Relying on overwhelming power here would defeat the entire point.
He exhaled slowly, rolling his shoulders and stretching his limbs to loosen the tension. His body responded smoothly, muscles relaxing as if preparing for a long hunt rather than a single fight.
The corridor ahead stretched into darkness, wide and tall, with jagged stone formations lining the walls. The uneven ground was scattered with old debris, shattered weapons, and fragments of bone.
Perfect terrain for ambushes.
Arthur narrowed his eyes.
"That skeleton earlier…" he thought. "I couldn't fully see it until I focused Keen Insight."
That meant something.
Either the dungeon enhanced their stealth, or these monsters possessed some form of concealment that interfered with perception.
Unacceptable.
Arthur activated both Six Eyes fully.
The world shifted instantly.
Layers of information unfolded before him. Airflow patterns, mana disturbances, pressure differences, faint killing intent embedded in the environment itself.
As he advanced, he kept his breathing slow and steady, every step measured.
Then—
A subtle disturbance.
Not sound. Not movement.
A draft.
Arthur's instincts screamed.
He snapped his head backward just as something sliced through the space where his face had been a fraction of a second earlier.
A sharp whistle echoed as the projectile embedded itself deep into the stone wall behind him.
An arrow.
"I can't rest for a single second," he muttered grimly.
His muscles tensed as his eyes scanned the darkness, but he didn't rush forward. That would be suicide.
A second arrow flew.
This one aimed lower.
Arthur twisted his body mid-step, narrowly avoiding the shot as it skimmed past his leg, the wind pressure brushing his skin.
He halted.
Not advancing.
Not retreating.
Observing.
A third arrow came, aimed at his left shoulder.
Then a fourth, directly at his chest.
The pattern was deliberate.
"They're testing me," Arthur realized.
The intervals between shots were consistent. The angles precise.
He began to move differently now, not dodging reactively, but predictively.
He paid attention to air displacement, to the faint tension in the cavern before each shot, to the killing intent that flared a split second before release.
His body adjusted.
He stopped thinking in terms of left or right, up or down.
He let instinct guide him.
Arrow after arrow flew.
Five.
Ten.
Fifteen.
By the twentieth, Arthur wasn't dodging anymore.
He was flowing.
His movements became economical, minimal, almost casual. A tilt of the head. A shift of weight. A half-step.
Finally, confidence settled into his bones.
He took a step forward.
Another arrow flew.
He dodged.
Two seconds.
Another step.
Another dodge.
Three seconds.
That was the rhythm.
"Now."
Arthur exploded forward.
His body surged with power, feet tearing across the ground as he sprinted straight toward the source. His eyes locked onto a faint silhouette ahead, barely visible against the cavern wall.
Three seconds.
The skeleton archer stood there, bow already drawn.
Arthur reached it just before the next shot could be loosed.
His kick shattered the bow cleanly, splintering it into useless fragments.
The skeleton froze.
Without its weapon, it hesitated.
That moment of confusion was fatal.
It tried to swing a clumsy punch.
Arthur slipped past it effortlessly, stepped behind, and twisted sharply.
Bone cracked.
The skull turned at an impossible angle before the body collapsed lifelessly to the ground.
Silence returned.
Arthur stood there for a moment, breathing steadily, adrenaline still humming beneath his skin.
Then the system's voice echoed.
---
[Congratulations, host]
[You have completed the first floor of the weekly training dungeon]
[You will be sent back]
[You have obtained 10,000 system points]
[You have obtained "Instinct"][
---
Before he could reflect on the reward, his surroundings blurred.
The cavern dissolved.
---
Arthur found himself back in the rest area, seated on the polished black stone floor near the bed.
Only then did he realize how exhausted he truly was.
Not physically.
Mentally.
Pushing his perception, calculating trajectories, suppressing panic while learning enemy behavior in real time had drained him far more than brute combat ever could.
He glanced at the skill description.
---
Instinct
Allows you to instantly identify the best possible course of action.
---
Arthur let out a low breath.
"A terrifyingly simple ability," he murmured.
But now he understood.
Instinct wasn't about knowledge.
It was about trusting yourself.
He lay down on the bed, muscles finally relaxing, his mind surrendering to rest.
Almost instantly, sleep claimed him.
He didn't know how much time passed, but when he opened his eyes again, his body felt light, refreshed, and clear.
With his mind clear and his body fully recovered, Arthur finally turned his attention to something he had deliberately postponed.
This conversation.
He sat upright on the stone bed inside the rest area and exhaled slowly, letting his senses spread inward instead of outward.
"Hey, Ddraig," Arthur said calmly. "I know you can hear me. I can feel your soul watching me."
There was no immediate response.
Arthur activated Keen Insight without restriction, letting his perception pierce straight through the layers of the Boosted Gear. The world peeled back like thin paper, revealing a vast inner space filled with dormant power.
At its center rested a massive European dragon.
Red scales layered like armor, eyes closed, presence immense and ancient. Even while silent, the dragon's existence alone carried overwhelming pressure.
Arthur folded his arms.
"How long do you plan to remain silent?"
Several seconds passed.
Then, at last, a deep, resonant voice echoed through the inner world.
"I have nothing to say to someone who stole my power."
Arthur blinked once.
Then he laughed.
Not a mocking chuckle, but a genuine, loud laugh that echoed through the space.
The dragon's eyes snapped open.
"What do you find so funny, human?"
Annoyance rippled through the dragon's voice.
Arthur wiped a tear from the corner of his eye.
"It's just that… so much time living with humans has really softened you, hasn't it? The great Ddraig, one of the Heavenly Dragons, sulking like a child who lost a toy."
A wave of pressure surged.
"You dare mock me?"
Arthur felt the world twist.
In an instant, his consciousness was dragged into a domain of raging crimson flames. Towers of fire rose endlessly, heat pressing down from every direction.
At the center stood Ddraig in his full glory.
A colossal dragon, scales gleaming like forged steel, eyes burning with ancient pride.
"Repeat your words, human."
Arthur could have resisted the pull. He knew that.
But he had come here willingly.
Black Anti-Magic erupted around his body, forming a dense, writhing aura that pushed the flames back several meters.
"I said you've gone soft," Arthur replied evenly. "You talk about me stealing your power, but that's nonsense."
His aura expanded further, the flames retreating step by step.
"That's how dragons act. If we want something, we take it. If someone else has it, we kill them and take it anyway."
Arthur met Ddraig's gaze without flinching.
"That kid was lucky to survive. But tell me, do you really have a problem with that? Or has the great Heavenly Dragon grown attached to a human brat?"
For a moment, the world trembled.
Then Ddraig laughed.
A deep, booming laugh that shook the flame domain itself.
"You're right," Ddraig admitted. "Being sealed for so many years has dulled my instincts. Dragons do not beg or complain."
He tilted his massive head.
"But answer me this. Aren't you human as well?"
Arthur smiled.
"Not entirely."
He stepped forward and lowered his guard.
"Use your senses. Look inside my chest."
Ddraig frowned, then focused.
For the first time, he truly observed his host.
And his expression changed.
Within Arthur's body beat two hearts.
One human.
One dragon.
Perfectly synchronized.
Not implanted. Not grafted. Not artificial.
Integrated.
Ddraig's eyes widened slightly.
"Interesting… transforming a human into a dragon is possible with time, but this is different. You were not modified. You were rebuilt."
Arthur nodded.
"I have a dragon heart. Dragon blood flows through me. Whatever I was before, I'm not just human anymore."
Ddraig studied him in silence.
Finally, he spoke.
"Very well. I officially recognize you as my host."
Arthur exhaled quietly.
"Now," Ddraig continued, "what do you want? You did not call me simply to argue."
Arthur did not hesitate.
"I want access to Balance Breaker. And Juggernaut Drive."
The flames surged violently.
Ddraig laughed again, louder this time.
"You are greedy. Power-hungry. Reckless."
Then his tone shifted.
"But you are not wrong. Your body could endure both."
Arthur inclined his head.
"I know the risks. Reduced lifespan, loss of control, destruction of everything around me. I accept them."
Ddraig snorted.
"Especially the second one. Juggernaut Drive is no joke."
"I know."
A long silence followed.
Finally, Ddraig spoke.
"Very well. I grant you access. Try not to get yourself killed too soon, young wielder."
Arthur smiled.
"I'll do my best."
The flame world dissolved.
Arthur returned to the rest area, opening his eyes with a quiet sense of satisfaction.
Everything had gone exactly as planned.
This was likely influenced by the protagonist's aura he had inherited. Ddraig's fondness for Issei had not vanished. It had simply found a new vessel.
Arthur clenched his fist slowly.
"Alright," he murmured. "Time for a few experiments."
Somewhere deep within the Boosted Gear, Ddraig watched.
And smiled.