[Location: The Ubuyashiki Estate] Time: Midnight
The moon hung high and full.
The bamboo gate creaked.
The grass withered beneath polished black shoes. Muzan Kibutsuji walked in. He wore a black tuxedo and a white fedora, looking less like a monster and more like a gentleman.
He had finally found it. The heart of the Demon Slayer Corps.
In the open room facing the garden, Kagaya Ubuyashiki already aware of Muzan's arrival, sat on his futon. His face was ravaged by the curse, bandages covering his blinded eyes, his skin mottled and purple. Yet he sat upright, dignified.
Beside him knelt his wife, Amane, and their two eldest daughters, Hinaki and Nichika. They held a mari ball and a fan, their expressions serene, showing no fear despite the devil standing five meters away.
"Welcome," Kagaya wheezed, his voice frail but steady. "I have been expecting you... Muzan."
Muzan looked down at the dying man with unmasked disgust. "You look terrible, Ubuyashiki. You smell like a corpse. How can someone so weak lead the Demon Slayer Corps?"
"I may be weak," Kagaya replied softly. "But my death will not stop the gears of fate. You and I... we are of the same blood. Your existence is the stain of our lineage."
Muzan's eyes narrowed, his pupils turning into vertical slits. "That history has no value."
"It does to us," Kagaya said. "And tonight... your dream of eternity ends."
Muzan stepped forward, the pressure of his aura cracking the floor. "You are dying. You can barely speak. What makes you so confident?"
He glanced at Amane. "Your wife shows no fear either. Your children are calm. How unnatural."
"She chose this path with me," Kagaya said, a smile touching his lips. He reached out, his trembling hand finding Amane's. "Thank you, Amane."
Amane lowered her head in silent agreement. "It is my honor, Oyakata-sama."
Muzan grew irritated. The calmness of these insects was insulting. They should be screaming. They should be begging.
He raised his right arm preparing to decapitate the entire family in one swing.
"Enough," Muzan stated. "This ends now."
Kagaya's smile widened just a fraction.
"I apologize..." Kagaya whispered. "This conversation must end here."
CLICK.
Beneath the floorboards, a hidden gramophone needle dropped onto a wax cylinder record. The sound was amplified by bamboo acoustics rigged throughout the garden, blasting a voice that Muzan recognized instantly.
It was Manjiro Asakura's voice.
"I... AM... ATOMIC."
Muzan froze. "—?!"
WHITE FLASH.
THE MANSION EXPLODED.
Fire, debris, and thousands of tiny Nichirin caltrops and shrapnel tore outward in a sphere of destruction.
Before Muzan could complete his strike, the blast wave hit him.
He was blown backward, his body shredded. The Nichirin spikes embedded themselves deep into his cells, searing his flesh and halting his regeneration.
"THEY BLEW THEMSELVES UP?!" Muzan roared, his body a mass of gore and fire. "FOR A TRAP?!"
Muzan, pinned by the shrapnel and regenerating slowly, glared at the crater where the family had been sitting. He expected to see charred bones.
He saw... nothing.
Just a deep, dark hole in the earth.
In the split second between Muzan raising his arm and the explosion triggering, Manjiro's plan was put in place.
[The Sengoku Drop Chute]
Trigger: The tatami mats Kagaya sat on were rigged with a counter-weight trapdoor (similar to ninja "Nindō" hidden doors). When Kagaya pressed a hidden switch, the floor dropped instantly.
The Masking: Yushiro, hidden in a reinforced bunker deep underground, activated a talisman, Blood Demon Art: Blindfold on the floor itself. To Muzan's eyes, the floor looked solid until the fire covered the view.
The Cushion: The family fell 10 meters into a sub-basement lined with thick cotton and water-filled cushions to break the fall without injury.
A heavy steel plate (Western import) slid over the hole a second after they dropped, sealing the bunker and shielding them from the blast occurring above.
['Muzan relies on hearing heartbeats and seeing blood flow,'] Manjiro's voice echoed in Kagaya's memory. ['But in an explosion? The sound is deafening. The heat masks body heat. He won't notice you dropping into the bunker until it's too late.']
Deep underground, the earth shaking above them, Kagaya Ubuyashiki coughed, safe in Amane's arms.
"It worked..." Kagaya whispered, tears of relief mingling with the dust. "Manjiro... your plan was perfect."
[Back on the Surface]
Flames and smoke rose from the destroyed estate, painting the night sky orange.
Muzan's body lay amidst the burning wreckage, damaged. He snarled, forcing the Nichirin fragments out of his flesh.
"That man..." Muzan growled, his face regenerating first. "He planted traps in his own home?! He used himself as bait?!"
THWIP.
Flesh seeds erupted from the smoke, turning into massive thorny vines that wrapped around Muzan, pinning him in place.
Tamayo emerged, using her Blood Demon Art to pin the regenerating Muzan, injecting the drug.
"DIE, MUZAN!"
"Tamayo!" Muzan screamed, his eyes widening. "You hypocrite!"
WHOOSH
GYOMEI HIMEJIMA descends from above, weapon swinging.
SANEMI SHINAZUGAWA follows immediately.
Gyomei Himejima slammed his spiked ball into Muzan's head, shattering it completely.
"Wind Breathing, Seventh Form: Gale, Sudden Gusts!"
He slashed Muzan's regenerating torso, wind blades shredding the flesh faster than it could knit together.
"THIS ENDS TONIGHT!" Sanemi roared.
Muzan blocked partially, his body twisting unnaturally. Bone whips exploding from his back to counter.
"Annoying insects..."
Giyu Tomioka and Tanjiro Kamado arrived from the flank, their blue water dragons intertwining to block the whips. Tengen Uzui threw a barrage of anti-demon bombs, forcing Muzan back.
"That presence..." Tanjiro gasped, his grip tightening on his sword. "There's no doubt. It's him! The scent of blood!"
"Stay focused!" Giyu barked. "One mistake means death!"
Muzan suddenly broke free of the vines and the chains, his shockwave blasting the Slayers back.
"You believe this trap will kill me?" Muzan hissed. "I will slaughter every one of you!"
"Do not let him escape!" Gyomei bellowed, swinging his axe.
Muzan slammed his hand onto the ground.
WARP.
The world dropped out from under them.
The tatami mats, the burning wood, the dirt—it all vanished.
"The ground—?!" Tanjiro yelled.
The Demon Slayers fell into an endless structure of shifting halls, floating rooms, and inverted architecture.
"Infinity Castle..." Giyu whispered, tumbling through the air.
The Slayers were scattered across different zones.
- Shinobu landed alone in a dark corridor. She began to run toward the scent of where the blood was coming from.
- Obanai, Mitsuri, Yushiro landed together on a shifting walkway, immediately sprinting toward the center.
- Tanjiro, Giyu, Genya, Rengoku landed on a rotating floor, immediately beset by a horde of lower-level demons.
- Tengen landed on a chandelier, tossing bombs at approaching lower demons.
- Gyomei & Muichiro landed side-by-side, their weapons ready, facing a long, dark hallway.
- Sanemi: Crashed through a wall alone, screaming in rage, slaughtering demons.
And...
Zenitsu landed on a quiet, floating pagoda. There were no lower demons. Just the sound of distant biwa strums.
He looked around, terrified. "Where... where is everyone? Tanjirou? Nezuko?!"
THUD.
Manjiro landed beside him.
"Yo," Manjiro said casually. "Looks like we got paired up, Pikachu. I wonder who's gonna be our opponent."
"Don't call me that!" Zenitsu shrieked. "Aniki! We're separated! We're gonna die!"
He looked across the bridge connecting the pagoda to the main structure.
A demon stood there. He wore a dark kimono and a familiar magatama necklace. Black lightning crackled around his horns.
Kaigaku. Upper Rank Six.
Zenitsu went quiet, shoulders stiff as the shaking finally stopped.
"Well," Manjiro muttered, "This is awkward."