🌙 Night – Gremory Mansion, Private Garden
The moon hung low and blood-red in the sky, its light casting long shadows across the Gremory estate. The sprawling gardens behind the mansion, usually serene, now throbbed with unease. Kaizen stood at the edge of the crimson-lit field, eyes locked on the strange formation in the sky above—a slow, swirling vortex of demonic energy, faint but growing.
He didn't need the AI's prompt to know something was coming.
Still, it whispered in his mind:
「Warning: Spatial fluctuations detected. Estimated convergence in 28 hours. High-energy entities converging near Kuoh.」
"Another incursion," Kaizen murmured to himself.
His hand instinctively drifted to the stone embedded in his palm—a manifestation of his Gearflow Core. The subtle hum of power pulsed through his body, syncing with the anomaly's tremors. This wasn't just a rogue devil or fallen angel. This was multiversal energy leaking through the cracks.
Behind him, soft footsteps approached. A familiar presence—Akeno.
"You've been quiet lately," she said, stepping beside him. Her usual teasing tone was subdued, replaced by thoughtful stillness. "Too quiet."
Kaizen offered a glance. "The calm before a storm."
Akeno nodded slowly, her gaze drifting to the unnatural glow above. "Rias felt it too. Whatever's coming... it's not local."
Kaizen's brow furrowed. "It's not just coming. It's already here."
---
⚔️ Earlier That Day – Training Hall
Kaizen's body moved with precision through a series of intricate sword forms, his energy blade humming with condensed magic. Rias, seated at the edge of the sparring floor, watched with critical eyes.
"You've improved," she said, finally breaking the silence.
Kaizen didn't stop. "Not fast enough."
"You're strong enough to stand beside us," she replied. "But your instincts... they're different. Sharper. Colder."
He sheathed his blade and turned. "I was built to survive wars. Not high school politics."
Rias stood and walked toward him. "You're not a weapon, Kaizen. You're a person. My peerage is a family, not a military unit."
"I don't have family," Kaizen said, voice steady but quiet. "Not in the way you mean."
Rias stepped closer. "You could."
Their eyes locked. A moment passed—unspoken promises, possibilities. But Kaizen pulled away first, distracted by a pulse of pressure on the edge of his senses.
「Alert: Dimensional rift destabilizing. Proximity breach.」
His eyes narrowed. "Something just crossed over."
---
💀 Meanwhile – Abandoned Church Ruins, Outskirts of Kuoh
The air shimmered and tore apart at the seams of reality. From the collapsing dimensional fabric stepped a figure cloaked in white, surrounded by swirling red glyphs that crackled with unstable power. The figure knelt, placing a single gloved hand against the earth.
"Target dimension stabilized," he muttered. "Prime fragment is present. Operation Extraction begins."
He rose—tall, pale, inhuman. His glowing silver eyes pierced the veil of night like twin spotlights.
Behind him, lesser beings—wraith-like soldiers—materialized, awaiting orders.
"Begin the hunt," he commanded.
---
📚 Later – Kuoh Academy, Occult Research Club Room
Issei paced the club room anxiously, while Kiba polished his sword and Koneko munched on a cookie with a frown.
"I'm telling you, something feels wrong," Issei muttered. "Like the air itself's heavy."
"Kaizen noticed it too," Kiba said, eyes serious. "And if he's worried, we should be preparing."
Rias entered the room, her usual composure visibly strained. "We don't have long. There's an incursion forming—Kaizen detected it first. It's not underworld-born. This is something else entirely."
Akeno followed, lightning crackling faintly along her fingertips.
"I'll reinforce the perimeter spells tonight," she said. "But if this thing is multiversal, barriers might not hold."
"Then we fight," Issei said firmly, fists clenched. "We've done it before."
"Not like this," Kaizen said, stepping into the room with grave calm. "This isn't just an attack. This is a retrieval."
Everyone turned toward him.
"They're not here to conquer. They're here for me."
---
🔥 Midnight – Forest Clearing Outside Kuoh
Kaizen stood before a hastily constructed sigil circle, etched in silver across the forest floor. Rias, Akeno, and Kiba flanked him, while Issei and Koneko kept guard on the perimeter.
He traced the runes with focused precision.
"This circle will let me interface with the breach. If I can stabilize it, I might slow their entry."
Rias frowned. "And if you fail?"
Kaizen looked up. "Then they won't wait for the front door. They'll tear a hole through Kuoh."
Lightning pulsed. Shadows twitched. A soft crack split the air—a warning.
Too late.
From above, the sky ruptured as the cloaked figure descended like a blade from the heavens. Power radiated from him like a tidal wave.
He landed gracefully, eyes fixed solely on Kaizen.
"Prime Fragment," he said. "Return to Origin. You were never meant to stay."
Kaizen stepped forward, energy humming from his form. "Then come take me."
Rias and the others drew their power.
But they would not get the first strike.
With a flash, the being launched forward—and the battle began.
---
⚡ Midnight – Forest Clearing Outside Kuoh
The enemy descended like lightning wrapped in shadow. Cloaked in a white mantle and surrounded by burning red glyphs, the interdimensional hunter moved with terrifying precision. The air howled around him, as if reality itself rebelled against his presence.
"Designation confirmed," he intoned, voice like steel against stone. "Prime Fragment Kaizen. Return now, and your universe will remain intact."
Kaizen stepped forward, power gathering beneath his skin. "That's not going to happen."
With a roar of impact, the enemy struck.
Kaizen's barrier barely formed in time. The explosion of force cracked the sigil circle beneath their feet, hurling shockwaves through the forest and flattening trees in all directions. Akeno's lightning surged to intercept, but the enemy's blade cut through it like silk.
Kaizen countered midair, his Gearblade forming in a flash of violet light. It clashed against the intruder's twin blades—ethereal and whisper-thin, yet indestructible. Sparks and screams of magic echoed through the clearing.
"You've grown since your fragmentation," the figure snarled. "But you're still incomplete."
"I don't need to be whole," Kaizen shot back, "to protect this world."
He shifted form.
In one blink, his skin rippled into hardened obsidian, arms stretching into sleek gauntlets with core lines glowing faint blue. A new ability—Phase Skin—from an earlier kill in another world, activated now for the first time.
Kaizen's next blow shattered the enemy's blade—only for it to regenerate midair.
"Impressive," the intruder said. "You've begun adapting."
Behind him, Rias charged her Power of Destruction into a condensed sphere and flung it at the enemy's back.
He didn't turn. The glyphs around him absorbed the blast.
Kiba flashed behind the enemy in a blur, dual blades slashing for the neck.
The enemy vanished.
Reappearing a dozen feet back, he gestured once—and dozens of shadow wraiths erupted from the forest edge, shrieking and howling.
"They're splitting us up!" Akeno warned, already weaving lightning shields around the perimeter. "Kaizen—!"
But Kaizen was already gone—teleported alongside the hunter into the sky by a forced rift jump.
---
🌌 Aetheric Subspace – Midair Combat Zone
They fell through the void between realms—neither earth nor air, but a liminal battlefield shaped by raw intent. Here, Kaizen's multiversal nature reacted with volatile force. His form pulsed and shimmered—skin flickering between human and something more. His eyes glowed violet.
The hunter spoke calmly as they fought midair, blades crashing and scattering starlight.
"You are the third shard I've tracked," he said. "The only one to survive this long."
Kaizen's voice was low and steady. "Then the others didn't want it badly enough."
With a flick of his hand, Kaizen released a pulse bind—a wave of paralyzing kinetic force. It slammed into the hunter and slowed him just enough.
Kaizen drove his blade into the hunter's chest.
Or tried to.
The blade stopped midway—caught by an invisible shield. The hunter smirked, then drove a spike of energy into Kaizen's side.
Pain flared. Kaizen screamed.
He dropped, spinning, crashing back down toward Earth like a meteor.
---
🔥 Kuoh City – Abandoned Shrine Grounds
He landed hard in the shrine courtyard, a crater forming beneath his feet. Dust clouded the air. Blood dripped down his side.
From the shadows, the hunter descended.
"Fragment retrieved," he whispered. "Prepare for synchronization."
Kaizen knelt, struggling to rise. Systems in his mind screamed warnings:
「Core breach imminent. Vital sync unstable. Tactical retreat advised.」
He ignored them.
"If I fall here… this world falls with me."
But before the hunter could finish his move—
—a beam of light lanced through the air and struck his shoulder, sending him skidding back.
A figure stepped from the shrine.
A girl. No older than 18. Dressed in white and violet robes, her long hair braided with star-metal thread, and her eyes—multicolored and ancient.
"Get away from my little brother," she said.
Kaizen stared. "…Aria?"
She nodded, glowing softly. "You forgot me again. As always. But I remember you."
The hunter snarled. "This realm was supposed to be sealed."
Aria smiled. "It was. Until you broke it."
Then she struck.
---
🌠Clash of Siblings and Stars
Together, Kaizen and Aria moved as one—one force of nature split across time and memory. She conjured rings of compressed magic around her arms and hurled them at the hunter, forcing him back. Kaizen charged in, blade reforged into a halberd made of light and kinetic mass.
They didn't just fight—they danced. Two beings made for combat, born of the multiverse and torn from it.
"You have her memories?" Kaizen asked, blocking a strike.
"Some," Aria replied. "Enough to protect you."
Their attacks pushed the hunter to the brink. His body cracked, his energy unstable.
"I will return," he growled. "And when I do, there will be no second warning."
With a final glyph, he vanished—slipping back into the dimensional cracks that had birthed him.
---
💔 Later – Gremory Mansion Infirmary
Kaizen lay shirtless on the healing bed, wrapped in white bandages, his side pulsing with faint blue light as healing spells worked.
Aria sat nearby, sipping tea, eyes calm but distant.
"You really don't remember me?" she asked.
"I'm… sorry," Kaizen said, voice hoarse. "You were part of what I lost when I fragmented."
Aria smiled faintly. "It's alright. You always forget. But I always find you."
Footsteps echoed.
Rias entered, eyes flicking between the two.
"You brought reinforcements," she said to Kaizen, though her gaze was firmly on Aria.
"Sister," Aria corrected gently, standing. "And I'm not here to stay."
"Why not?" Rias asked.
"Because the real war hasn't even begun," Aria said. "And he's only just waking up."
She looked to Kaizen. "Remember who you are. Before the others come."
And with that, she stepped into a glyph—and vanished.
Rias slowly turned to Kaizen. "You really are full of surprises."
He looked away. "I wish I wasn't."