It was late at night.
Leo dropped in at the Gosha Academy rooftop.
He sighed blindfolded still on. "Why must I be the one to send to investigate the glowing classroom".
He sighed as he opened the door and started to walk down.
Leo went to where everyone saw the glow, the 5th floor.
He opened the door, and walked around, his footsteps making no sound.
He was hiding in the shadows, as he rushed at it.
His Taima particles felt it
He moved his head he felt a light, he decided to remove his blind fold too see the classroom glowing.
He looked at it. 'Found it'
He opened the door, and once he did, he saw it was like a ritual going on.
There in the centre was Morino Yuuko, wearing an interesting outfit.
Leo blinked. 'Wait no, this was not part of the original plan, she should not be doing this as highschool student'.
Leo opened the door as Yuuko stopped as the spell backfired.
She saw who opened and it was Leo. "Leo Kun"
Leo then got blasted as she closed her mouth.
Leo got sent back, as he hit the wall. 'I'd better not turn into a Tentacle monster'.
Once Leo woke up, he felt his head was on something soft
He looked around as his head was resting on someone's lap, and he looked up to see if it was Yuuko.
Leo groaned softly.
"Please tell me I didn't just die and wake up in a weird afterlife."
Morino Yuuko yelped a little.
"You– you're awake!"
Leo shifted, then froze.
…Warm.
Soft.
Definitely someone's lap.
He slowly looked up.
Purple hair.
Big witch hat tossed to the side.
Cape draped awkwardly over her knees.
"…Oh," Leo said. "Hi."
Yuuko's face went bright red.
"I– I'm so sorry! You hit the wall really hard and you wouldn't wake up and I panicked and I didn't know what to do so I just dragged you away from the circle and–"
"It's fine," Leo said quickly. "You're doing great. Ten out of ten bedside manner."
He sat up, touching the side of his head.
"Still human," he muttered.
"Still not covered in tentacles. Good start."
Yuuko blinked.
"…Tentacles?"
"Long story. Bad ending in most versions."
Leo looked around the classroom.
The ritual circle was half-burned into the floor.
Black wax candles melted into ugly blobs.
Symbols still faintly glowing.
"…You were summoning something," Leo said.
Yuuko squeezed her staff.
"I– I was trying to bind a familiar."
Leo raised an eyebrow.
"At midnight. In a sealed classroom. With demonic runes."
She shrank a little.
"…A strong familiar."
"Yeah," Leo said dryly. "You almost got the hentai edition."
Yuuko bit her lip.
"I didn't mean for it to go wrong. The spell was from my grandmother's grimoire. It said the familiar would respond to magical resonance and–"
"And my Taima particles walked in and said 'hello there,'" Leo finished.
She stared at him.
"…Your what."
He waved a hand.
"Ninja anti-demon energy. Long story. Family thing."
Yuuko stared harder.
"…You're a ninja."
"Also long story."
They both just sat there for a second.
Then:
"…So," Leo said. "You're a witch."
"…So," Yuuko said. "You almost got turned into a tentacle monster."
They nodded at the same time.
Yuuko suddenly bowed so hard her hat fell off again.
"I'm really, really sorry, Leo-kun! I didn't mean to hurt you! Or curse you! Or corrupt you! Or—"
"It's fine," Leo said. "I've been stabbed this week. You're still behind schedule."
That made her pause.
"…What kind of school is this."
"Bad one."
Leo stood up and walked to the circle.
He crouched and touched one of the burned symbols.
"…You were trying to call something from the astral layer. Not hell. Not demon space."
Yuuko's eyes widened.
"You can read this?"
"Kinda," he said. "More like… feel it."
He rubbed his chin.
"…Yeah. That thing that answered you wasn't a familiar."
Her voice came out tiny.
"…What was it."
Leo looked back at her.
"Something hungry."
Yuuko went pale.
"…It's still here, isn't it."
Leo closed his eyes.
Spread his Taima particles gently.
Felt something… thin.
Coiled.
Watching.
"…Yeah," he said quietly. "It didn't get what it wanted. So it's waiting."
Yuuko gripped her staff with shaking hands.
"I– I can undo the spell. I think. Maybe. If it doesn't eat me first."
Leo cracked his neck.
"Cool. You focus on the spell part."
He turned his blindfold back toward his eyes, then paused.
"…And I'll handle the tentacle problem."
Yuuko stared.
"…You sound way too calm about that."
Leo smirked.
"I've had worse nights."
Leo slowly flexed his right arm.
Blacklight crawled over his skin like liquid ink.
"…So," he said. "Your spell hit me, right?"
Yuuko nodded, nervous.
"Yes. It should have bonded whatever answered the summon to you."
Leo lifted his arm.
The Blacklight twitched.
Then something pushed out of it.
A tentacle formed—thicker than his usual tendrils.
Hard ridges ran along it.
Sharp spikes jutted out like barbs on a spear.
It snapped once in the air.
Yuuko gasped.
"Th– that's not normal…"
Leo stared at it, rotating his wrist.
"…Yeah. That's new."
The tentacle pulled back into his arm, melting into Blacklight again.
He frowned.
Then his eyes widened slightly.
'The Blacklight absorbed it,' he thought.
'It didn't reject the spell. It ate it.'
He looked back at Yuuko.
"…You didn't bind a monster to me."
She swallowed.
"…Then what did I do?"
Leo smirked, half impressed, half uneasy.
"You upgraded me."
Yuuko blinked.
"…I— I what."
The air in the room suddenly went cold.
The half-burned ritual circle pulsed.
A wet, dragging sound came from the far wall.
Leo's smile faded.
"…Okay. Bad news."
Yuuko grabbed her staff.
"It's manifesting, isn't it."
"Yeah," Leo said. "And it's pissed I stole its lunch."
A shadow peeled itself off the wall.
Too many joints.
Too many limbs.
Tentacles sliding across the floor, leaving black slime behind.
One long feeler lifted and sniffed the air.
Yuuko backed up until she hit a desk.
"I– I can't finish the banishment chant like this!"
Leo stepped forward.
Blacklight rolled down his arm again.
The new spiked tentacle burst out—longer this time.
Thicker.
Heavier.
"…Good," he said quietly.
"Because I want to test something."
The creature lunged.
Leo swung.
The spiked tentacle tore through the air and slammed into it.
There was a wet crack.
The thing screeched.
Leo's eyes widened in surprise.
"…Oh."
He grinned.
"…Yeah. You definitely made me stronger."
The creature shrieked as it slammed into the wall.
Its body rippled, bones bending the wrong way as it pulled itself upright again.
Black veins spread across the floor beneath it.
The desks nearest to it began to rot—wood turning soft, metal rusting in seconds.
Yuuko stared in horror.
"It's corrupting the classroom…"
Leo cracked his neck.
"…Rude."
Blacklight surged down both his arms.
His right arm reshaped first.
The spiked tentacle burst out again—but this time it flattened, widening and curving.
Hard biomass layered over it.
Spikes locked into place along the edges.
In three seconds, it became a massive jagged shield fused directly to his forearm.
Yuuko's eyes went wide.
"…That form— that's demon-grade biomass armor."
Leo lifted the shield and tested the weight.
"…Okay. That's cool."
The creature lunged again.
Leo planted his foot.
The shield took the impact.
The spikes sank into the thing's flesh.
It screamed.
Leo's left arm twisted.
Three thinner tentacles shot out and wrapped around the creature's torso.
He yanked.
It slammed face-first into the floor.
Leo tilted his head.
"…What if I do both?"
The shield split down the middle.
From its center, a massive spiked tentacle erupted forward like a battering ram.
It punched straight through the creature's chest and pinned it to the far wall.
Yuuko covered her mouth.
"That… that fusion form…"
Her knees went weak.
'So this is it,' she thought.
'The Fuuma clan demon trigger'.
She looked at Leo with fear and awe.
"…You're not human, are you."
Leo glanced back at her.
"…Uh. That's rude."
The creature suddenly convulsed.
Its body swelled.
More limbs tore out of it.
Eyes opened along its torso.
The corruption spread faster now.
The ritual circle flared red.
The walls began to melt.
Yuuko screamed.
"It's adapting!"
Leo looked around.
Then down at the black veins crawling toward Yuuko's feet.
His smile vanished.
"…Yeah. No."
Blacklight exploded off his body.
A wave of black biomass rolled across the floor like a tide.
It swallowed the corruption.
The black veins stopped.
Then reversed direction.
They flowed back into Leo.
The creature shrieked as its own corrupted mass was ripped out of it.
Yuuko stumbled as the pressure dropped.
Leo stepped in front of her.
"Stay behind me."
The thing tried to flee.
Leo raised his arm.
The spiked tentacle-shield reformed.
But this time, the spikes opened like jaws.
Blacklight poured out.
It wrapped around the creature.
The creature screamed.
Then its body collapsed inward.
Every tentacle, every limb, every eye was dragged into Leo's arm.
The room went silent.
The glow died.
The ritual circle faded.
The desks reformed.
The walls hardened again.
Leo exhaled.
"…Huh."
Yuuko stared at him in pure shock.
"…You just absorbed an eldritch entity."
Leo flexed his arm.
The Blacklight rippled once.
"…Yeah. Guess I did."
He looked back at her.
"You okay?"
She nodded slowly.
"…Y– yes…"
Then she bowed deeply.
"I'm so sorry. I summoned that thing. I endangered the school. I endangered you."
Leo waved his normal hand.
"Eh. I've had worse Tuesdays."
Yuuko hesitated.
"…So… the demon inside you…"
Leo blinked.
"…The what."
She looked at him with absolute seriousness.
"The Fuuma clan's sealed demon. The one that devours curses and outer beings."
Leo froze.
'…Oh. That explains everything,' he thought.
"…Yeah," he said carefully.
"Let's go with that."
Yuuko nodded, convinced.
"…Then my spell didn't corrupt you."
She clenched her staff.
"It awakened it more."
Leo forced a calm smile.
"…Sure. Let's call it that."
Leo looked at Yuuka as he made the Tentical again. "So like, how does this thing get enegry".
Yuuko flipped through her spellbook again, cheeks turning pink.
"Well you see—"
Leo leaned closer.
"Go ahead. Tell me."
She swallowed.
"…It feeds on pleasure-based energy."
Leo blinked.
"…Define that before I panic."
Yuuko adjusted her glasses.
"Strong emotional and physical sensations. Excitement. Intimacy. Deep affection. Adrenaline spikes. Romantic attachment."
She hesitated.
"…Also sexual pleasure, yes, but that's only one subcategory."
Leo exhaled.
'Oh thank god, it's not just hentai fuel.'
"…So it's basically powered by vibes."
Yuuko nodded weakly.
"…Very intense vibes."
Leo looked at his arm as the Blacklight rippled once.
"…That explains why it didn't activate when I was fighting that thing."
Yuuko froze.
"…Why not?"
Leo shrugged.
"I was annoyed. Tired. And mostly thinking about how I didn't want my fiancée to kill me for being out late."
The tentacle twitched.
Then retracted slightly.
Yuuko's eyes widened.
"…It responds to emotional state too."
Leo stared.
"…So if I'm happy—"
The Blacklight pulsed.
"…It gets stronger."
Yuuko went very, very still.
Her face went red.
Her heart started pounding.
'He's calm. He's strong. He saved me. He protected me without hesitation. He absorbed an eldritch god like it was homework.'
Her knees weakened.
"…Y– you're amazing, Leo-kun."
Leo looked at her.
"…You okay?"
She suddenly grabbed his sleeve.
"I– I swear myself to you!"
Leo flinched.
"…You what."
"As your mage. Your familiar. Your support unit. Your magical logistics officer. Your—"
She stopped herself.
"…Your person."
She bowed deeply.
"I will help you control that power. I will research it. I will make sure it never hurts you. Or anyone you love."
Leo scratched his head.
"…That's a lot of responsibility for a Tuesday night."
She looked up at him, eyes shining.
"…I'm not afraid of you."
Then quietly:
"…I'm in love with you."
Leo froze.
The Blacklight glowed softly.
"…Oh no."
Yuuko noticed.
"…Did it just get stronger."
Leo sighed.
"…Yeah."
She gasped.
"…So my feelings are—"
"—fueling the eldritch arm, yes."
She looked at his arm.
Then at him.
Then back at his arm.
"…That's the most romantic and horrifying sentence I've ever heard."
Leo rubbed his face.
"I really, really have things to explain to my fiancée."
Yuuko straightened instantly.
"…Fiancée."
"…Yeah."
She wilted for half a second.
Then stood taller.
"…Then I will support you as your devoted mage."
Beat.
"…With completely inappropriate feelings I will never act on."
Leo gave her a tired smile.
"…Appreciated."
The Blacklight pulsed once more.
Yuuko whispered:
"…It likes you smiling."
Meanwhile, across the multiverse — inside the Blacklight Hive Mind
A vast black-and-violet void pulsed with slow, organic light.
Data streams. Sensory echoes. Emotional spikes.
Then—
Alex doubled over.
"—WHY DOES MY STOMACH HURT?!"
He dropped to one knee, clutching his gut.
"This is psychosomatic. I do not possess a stomach. I am a distributed consciousness construct!"
The Hive around him rippled.
A new data thread lit up:
[NEW MODULE DETECTED
Tentacular Manifestation — Type: Eldritch/Weapon Hybrid
Power Source: Emotional–Pleasure Energy
Bond Anchor: Yuuko Morino
Host: Leo Fuuma]
Alex's eye twitched.
"…Oh no."
Across the void, James stood with his arms crossed, watching a holographic replay of Leo's arm forming the spiked tentacle-shield fusion.
The footage showed Leo laughing as he absorbed the eldritch corruption.
James stared.
"…The hell?"
The replay zoomed in.
Blacklight tendrils weren't just copying the spell.
They were improving it.
Adding structural reinforcement.
Adaptive edges.
Energy feedback loops.
James squinted.
"…Why does that look like one of my old combat concepts."
Alex staggered back to his feet.
"James."
"…Yeah?"
"We have a problem."
James didn't look away from the hologram.
"Let me guess. Leo just accidentally unlocked a romance-powered anti-eldritch super-weapon."
Alex pointed at the display.
"It feeds on emotional intimacy. Affection. Romantic attachment. Pleasure-adjacent neural spikes."
James finally turned his head.
"…You're joking."
Alex's voice went flat.
"I am never joking when my nonexistent organs hurt."
The Hive pulsed again.
Another alert.
[WARNING
Bond Strength Increasing
External Emotional Anchor Stabilizing Core
Blacklight Growth Rate: +312%]
James slowly rubbed his face.
"…He met a mage girl, didn't he."
Alex nodded.
"…He met a mage girl."
James sighed deeply.
"…Of course he did."
Back in Leo's world — subtle cut
The Blacklight pulsed warmly around Leo's arm.
Yuuko, standing way too close to him, whispered:
"…It feels… calmer now."
Leo frowned.
"…Huh."
The tentacle curled slightly toward her.
Protective.
Almost affectionate.
Leo's eye twitched.
"…Why does my arm look like it's simping."
Back in the Hive Mind
Alex collapsed into a chair that shouldn't exist.
"This violates at least seven cosmic safety protocols."
James shrugged.
"…Kid turned eldritch horror into a girlfriend-powered support weapon. I'm honestly impressed."
Alex groaned.
"We left him alone for three days."
James smirked.
"…And he speedran a new evolution tree."
The Hive pulsed again.
[NOTICE]
Blacklight Subroutine Created:
PROTECT YUUKO MORINO — Priority Level: ABSOLUTE
Alex screamed into the void.
"WHY IS HE LIKE THIS?!"
James laughed.
"…That's our boy."
To be continued
Hope people like this Ch and give me power stones