Muzan Kibutsuji

The night was as dark as ink, silently Ubuyashiki residence. The stone lanterns in the courtyard emitted a dim, yellowish glow, barely illuminating the winding corridors.

Kagaya Ubuyashiki sat on the tatami mat in the main room, his back ramrod straight. His eyes had long been blinded by the curse, and his face was wrapped in white bandages, yet it seemed as if he could see through the gaps in the fabric to the courtyard. His wife, Amane, knelt beside him, her hands folded on her knees, her posture dignified and calm, only her slightly white knuckles betraying the tension deep within her heart.

Outside the mansion, a cold, viscous aura, seemingly capable of freezing the soul, was slowly approaching.

There were no footsteps, only an invisible sense of oppression, like the pressure of the deep sea, grinding through the air inch by inch. The chirping of insects in the courtyard had completely disappeared at some point, and even the wind seemed to have frozen.

The shoji doors were silently pulled open.

A figure appeared outside the door amidst the atmosphere of dry ice.

He was a man who looked to be about thirty years old, dressed in a well-tailored black Western-style suit with a dark red bow tie. His hair was neatly combed back, revealing a flawless, pale face.

He stood there, not immediately coming in, but slowly scanning the room with his eyes. Wherever his gaze fell, the air seemed to thicken.

"You've finally come to me." Kagaya Ubuyashiki spoke first, his voice gentle and steady, as if welcoming a late guest. "Muzan Kibutsuji. The demon that our clan and the Demon Slayer Corps have been hunting for a thousand years."

Muzan's lips curled into a mocking smile, but he remained silent.

Ubuyashiki turned to his wife beside him. "Amane, what does he look like?"

Amane's gaze fell on the figure outside the door, her voice soft yet clear. "He looks to be a man nearing thirty, wearing a black tuxedo. However... his eyes are magenta, and his pupils are as slender as a cat's."

"I see." Ubuyashiki nodded slightly, as if confirming something. "Muzan, I knew you were coming. After all, you must be quite angry with the Ubuyashiki Clan and the Demon Slayer Corps. So I thought you would come to kill me yourself."

Muzan finally stepped inside.

His movements were as elegant as a nobleman attending a banquet, each step precise and composed. But his crimson eyes remained fixed on Ubuyashiki, churning with a thousand years of accumulated hatred and contempt.

"I'm utterly disappointed, Ubuyashiki." Muzan's voice was low and chilling. "The lord of my clan, who has been an obstacle for a thousand years, is actually like this."

His gaze fell on the bandaged face of the Ubuyashiki, then swept over his thin body.

"Ugly." Muzan slowly uttered the word, "Truly hideous. I can already smell death emanating from you, Ubuyashiki."

A faint smile appeared on Kagaya Ubuyashiki's face.

"I thought so too. Six months ago, the doctor told me I would die within days." His voice remained calm. "Despite that, I'm still alive. That's because I'm determined to defeat you, Muzan."

Muzan's pupils contracted slightly.

"That illusory dream will shatter tonight." His voice turned cold. "I will kill you next. Then, I will find the Blue Spider Lily and complete my final evolution. At that time, even the sunlight will no longer be able to threaten me."

"You may not know this," Ubuyashiki continued, seemingly ignoring his threat, "But you are actually from the Ubuyashiki Clan. However, you were born over a thousand years ago, so our bloodline isn't that close."

Muzan frowned.

"I don't have those useless emotions." His voice betrayed impatience. "What do you want to say?"

"Because a monster like you appeared in our clan, our entire family is cursed, and our children die shortly after birth." Ubuyashiki's voice carried a heavy tone. "Under the guidance of the shrine, we must kill you to break the curse. For generations, we have married women from priestly families, and our children no longer die so young. Even so, our clan... still cannot live past thirty."

A brief silence fell over the room.

Then, Muzan.

It was a mocking, cold laugh that came from deep within his throat.

"Utterly absurd." He shook his head, as if he had heard the most ridiculous joke. "Disgusting. Will your illness spread to your brain? There's no cause and effect whatsoever."

His voice suddenly rose, and a terrifying light flashed in his crimson eyes:

"The reason is simple—because I have not suffered any divine retribution! Even after killing thousands of people, Heaven still allows my existence! In these thousands of years, I have never seen a god or Buddha punish me!"

The moment the words left his mouth, Muzan's aura suddenly surged.

It wasn't murderous intent, but something more primal and cold, as if it were the end of all things, the opposite of life. The air began to distort, the indoor temperature dropped sharply, and even a thin layer of white frost condensed on the tatami mats.

Amane Ubuyashiki's body tensed instantly. She could sense that Muzan to make his move.

But Kagaya Ubuyashiki remained seated, his face beneath the bandages as calm as still water.

Just then--

Space distorted slightly.

It was an extremely subtle fluctuation, so subtle that it was almost imperceptible. Even the flow of air remained unchanged, and the projection of light and shadow was normal. But in that instant, a figure seemed to materialize from nothingness, silently appearing behind Muzan.

White hair, black eye patch, and a dark blue Demon Slayer Corps uniform.

Moyu.

His appearance came without any warning, without any leak of his aura. It was as if he had always been standing there, only that no one had seen him before. Even the immense pressure that Six Eyes himself exuded was now completely contained, like an undercurrent beneath the deep sea, calm and still on the surface.

He held a specially made syringe in his hand. Inside the syringe, four colors of medicine had been perfectly mixed, presenting an eerie dark purple color that shimmered faintly under the light.

Muzan's senses were Muzan sharp. In the fraction of a second that Moyu appeared, every cell in his body emitted a piercing alarm. Danger! Deadly danger! Attacking from behind!

But it was too late.

Moyu's movements were frighteningly concise. There were no unnecessary movements, not even a whiff of wind. He simply raised his hand, aimed the syringe needle at a Muzan spot on the back of Wuzan's neck, and then plunged it in.

The needle tip penetrates the skin and muscles, precisely piercing the blood vessels.

"What--?!"

Muzan's pupils suddenly contracted to the size of pinpoints. He whirled around, his arm transforming into a ferocious claw, sweeping backward with the force to tear through space!

But Moyu had already completed the injection.

The dark purple liquid inside the syringe was instantly injected into Muzan's veins under high pressure. At the same time, Moyu gently pressed his other hand on Muzan's back, giving it a light push.

But that push contained the repulsive force of "Haku". Muzan's body was as if struck by an invisible giant hammer, and he was sent flying forward uncontrollably!

"Bang--!"

The wooden shoji gate was smashed to pieces. Muzan's figure flew out of the gate like a cannonball, streaking across the courtyard and crashing heavily into the woods outside the mansion. The enormous impact shook the ground, and the cracking sound of trees breaking was particularly jarring in the night air.

All of this happened in the blink of an eye.

From the Moyu appeared to the completion of the injection and the moment Muzan was Muzan away, the entire process took less than two seconds.

Amane Ubuyashiki hadn't even realized what had happened. She only saw Muzan turn around, and then fly out, the shoji door shattering, and the night wind rushing into the room.

Moyu was already standing in the spot where Muzan had originally been.

The syringe in his hand was empty. He casually tossed the syringe onto the ground, the sound of shattering glass crisp and cold.

"Moyu... Lord?" Amane's voice trembled slightly.

Moyu did not respond. His gaze, peering through the black eye patch, fell upon the woods outside the mansion. His six-eyed senses had already locked onto Muzan's location—the energy source that was now running rampant.

"You all leave first," Moyu said calmly. "Go to the Butterfly Mansion. Stone Hashira will be here soon."

Before the words were finished, heavy footsteps could be heard outside the courtyard.

The imposing figure of Gyomei Himejima appeared outside the broken doorway. A huge Buddhist rosary hung around his neck, his hands were clasped together, and two tear streaks on his face gleamed faintly in the moonlight.

"Namo Amitabha Buddha..." His voice was deep and resonant, like the tolling of a bell. "Lord Moyu, I have arrived."

"Take them with you first," Moyu repeated, his tone now carrying an air of unquestionable authority.

Without Gyomei, Xingming strode into the house and knelt before the Ubuyashiki couple, his massive body bowing low. "My Master, my lady, please come up. I will carry you away."

Kagaya Ubuyashiki nodded gently and, with Amane's support, leaned against Gyomei's broad back.

"Moyu- kun..." Ubuyashiki whispered, "Be careful."

Moyu nodded slightly.

Gyomei carried the two on his back and strode heavily towards the Butterfly Mansion. He was incredibly fast; each step he took caused the ground to tremble slightly, and his imposing figure quickly disappeared into the night.

Now, only Moyu remains in the main house.

He slowly walked out the door and into the center of the courtyard. Moonlight shone on his white hair, making it gleam silver. His black eye patch was almost invisible in the night, only his concealed eyes were visible, watching the increasingly violent energy in the woods.

In the woods.

Muzan slowly rose from the broken tree trunk.

His dress was torn, and on the exposed skin, dark purple veins were bulging and throbbing abnormally. He could feel something spreading within him—not poison, at least not in the way he understood poison. It was something more complex and bizarre, interfering with his cell regeneration and disrupting his energy cycle.

What shocked him even more was that attack just now.

It wasn't the syringe, but that push. That invisible force was precise, powerful, and irresistible. And the way that white-haired man appeared was completely without warning, as if he was always meant to be there.

"Who is it..." Muzan's voice was forced out through clenched teeth, his crimson eyes burning with rage in the darkness, "Who is that white-haired man?!"

He suddenly looked up, towards the direction of the mansion.

He could sense that the person was still there. They hadn't chased after him, but were simply waiting quietly.

"Arrogant..." Muzan smile appeared on Muzan's face. He raised his hand, and the skin on his arm began to writhe and deform, turning into countless thin, black thorns. The tips of those thorns were as sharp as needles, and their surfaces gleamed with a cold, metallic light, resembling the tentacles of death in the moonlight.

Black Blood Brambles.

This is one of his most frequently used Blood Demon Art. It transforms his own blood into thorns, each one containing deadly poison and terrifying destructive power.

"No matter who you are..." Muzan strode towards the mansion, "I will tear you to pieces. Then, I will find the antidote for that injected substance... I..."

The words abruptly stopped.

Because the moment he took his third step, a figure appeared at the edge of the woods.

Moyu.

He had left the mansion courtyard at some point and stood there quietly, at the boundary between the woods and the mansion, at the dividing line between moonlight and shadow.

The night wind ruffled the ends of his white hair, and his face beneath the black eye mask was eerily calm.

"You..." Muzan's pupils contracted again.

He could sense that the aura emanating from this person... was off. It wasn't a matter of strength or weakness, but a fundamental difference.

Moyu didn't give Muzan time to think.

He raised his right hand, his index and middle fingers together, the tips pointing in the direction of Muzan.

Then, with a gentle flick.

"Spell Reversal - 'Her'."

The instant Moyu finished speaking, the space in front of his fingertips suddenly twisted, compressed, and then—

Break out.

A dark red beam of light shot out from Moyu's fingertips.

The manifestation of a pure, extreme repulsive force is the result of space itself being forcibly repelled, compressed, and then blasted forward.

Wherever the beam of light passed, the air was completely evaporated, leaving a vacuum trail. The ground was plowed with deep furrows, and the soil and rocks on both sides were directly Annihilation into the most basic particles, leaving not even ashes behind.

Speed, extremely fast.

Muzan even have time to think. Every cell in his body was urging him to escape. But his body's movements couldn't keep up with the speed of his thoughts.

He could only watch helplessly as the dark red beam of light pierced through the dozens of layers of Black Blood Brambles defense he had hastily erected in a fraction of a second. Those thorns, which were strong enough to withstand the full force of a Pillar-level swordsman's strike, melted, Annihilation, and disappeared the moment they came into contact with the beam of light, just like ice and snow under the sun.

Then, the beam struck his body.

The left shoulder, along with the entire left arm and a small portion of the chest.

There was no sound, or rather, the sound was Annihilation too quickly to travel.

Muzan felt a void, a void more terrifying than pain, as if a part of his existence had been erased. He looked down and saw that his left half, from his shoulder to his waist, a full third of his body, had disappeared.

It vanished completely and cleanly, as if erased from the world by an eraser. The cut was smooth as a mirror, with no blood gushing out, because even the blood vessels had been instantly Annihilation and sealed off.

His remaining body staggered backward, crashing into another large tree behind him and snapping it in two.

"No... impossible..." Muzan's voice trembled, and for the second time, genuine fear flashed in his crimson eyes. "What... what power is this?!"

He could sense that the regeneration of the Annihilation parts was terrifyingly slow. It wasn't that it was being suppressed, but rather that the very concept of regeneration had become blurred in that part of the body.

In the distance, Moyu had already lowered his hand.

He gazed at Muzan's mutilated body, his six eyes analyzing the effects of the drugs within him. Four drugs were spreading, fusing, and taking effect in Muzan's blood: Aging, Poisoning, Regeneration Suppression, and Division Inhibition —each was slowly but steadily eroding the body of this thousand-year-old Demon King.

Not fast enough. But that's okay.

Moyu raised her hand again.

But just as energy condensed at his fingertips, Muzan suddenly raised his head and let out a silent roar at the night sky.

That was not a sound, but a deeper call transmitted through blood.

Nakime--!

Almost at the same moment.

The ground beneath Moyu's feet vanished without warning.

No, it didn't disappear, but opened up. A square passage about three meters in diameter appeared out of thin air beneath his feet. At the other end of the passage was an upside-down wooden corridor, a spiral staircase, and countless opening and closing doors—a Japanese castle that stretched infinitely, defying all the laws of physics.

Infinity Castle.

Meanwhile, on the other side of the forest, Gyomei Himejima had just escorted the Ubuyashiki couple to safety and was about to return to the battlefield to provide support when the same passage appeared beneath his feet.

Nakime's Blood Demon Art: Space Manipulation.

She intends to drag these two strongest Pillars into the Infinity Castle and defeat them on Muzan's home turf.

A powerful suction force emanated from the passage. Gyomei Ming's burly body began to fall. He let out a low growl, his arm muscles bulging as he tried to resist the force, but the ground beneath his feet had become nothingness, leaving him with nowhere to hold on.

As for Moyu, he offered no resistance.

He let his body fall completely into the passage. As he fell, he turned his head and looked in Gyomei's direction.

Then, he raised his hand.

"Azure."

An invisible gravitational field unfolded above Gyomei, exerting gravity on Gyomei.

Gyomei's body was as if grabbed by an invisible hand and pulled out of the passage, landing heavily on solid ground outside the passage's boundaries.

"Moyu--!" Gyomei's exclamation rang out.

Moyu, however, was already falling.

But he didn't stop. Mid-fall, he calmly said something in Gyomei's direction:

"Gyomei, leave him to me."

The sound wasn't loud, but it clearly pierced through the distortion of space and reached Gyomei's ears.

"My capabilities... are rather difficult to control."

As soon as he finished speaking, Moyu's figure disappeared into the depths of the passage. The passage began to contract and close.

"Moyu Yu--!"

Another voice came from the other side of the mansion.

Shinobu Kocho.

She didn't come alone. Behind her were Kyojuro Rengoku, Giyu Tomioka, Tengen Uzui, Mitsuri Kanroji Muichiro Tokito, Sanemi Shinazugawa, Obanai Iguro —all the Pillars had arrived.

They received a message from the crows informing them that a demon had attacked the Ubuyashiki, and rushed there as quickly as possible. But in the end, they were too late.

All they saw was a broken courtyard, a messy woods, Stone Hashira standing in an open space, and Moyu falling into a strange passage that appeared out of nowhere.

"What... is that?!" Mitsuri covered her mouth, her light green eyes filled with horror.

"The Infinity Castle," Gyomei Himejima's voice was heavy, "Muzan's lair. Lord Moyu... has entered it voluntarily."

"What?!" Sanemi's temples bulged with veins. "That bastard--!"

Shinobu had already rushed forward.

Her speed exploded to its limit; the "Insect Breathing" technique made her resemble a real purple butterfly, leaving afterimages across the night sky. She was going to rush into that passage; she wanted to go in with Moyu—

But it was too late.

Just as her fingertips were about to touch the edge of the passage, it closed.

Like ripples on water returning to calm, the passage vanished, the ground returned to its original state, and Ren's fingertips only touched the cold soil.

She knelt on the ground, her fingers digging deep into the soil.

Her violet eyes were fixed on the spot where Moyu had disappeared, her pupils trembling.

"Why..." Her voice was very soft, almost inaudible, "Why... didn't you wait for us..."

The other pillars also rushed over.

Kyojuro Rengoku crouched down to examine the ground, but there was nothing there. Giyu Tomioka watched silently, his hand on the hilt of his sword, his knuckles white...

"Namo Amitabha Buddha..." Gyomei Himejima his hands together, tears streaming down his face. "Moyu said... his abilities are difficult to control. He doesn't want to affect us."

"Bullshit!" Sanemi Shinazugawa slammed his fist on the ground, sending dirt flying. "That doesn't mean you have to go in alone! That's Muzan's lair!"

"But Moyu- kun... is indeed the strongest." Shinobu Kocho slowly stood up, her gentle, formulaic smile returning to her face, but something burned deep within her purple eyes. "Now that he's in, we must trust him."

She turned and looked at the other pillars.

"Everyone, our Master and his wife are safe. Now, what we must do is—" Her voice suddenly turned sharp, "Immediately seal off this area and be on alert for any other ghosts that may appear. At the same time, prepare for battle at any moment."

"Moyu- jun is fighting inside," Ren said, enunciating each word clearly. "We, on the outside, must also do what we're supposed to do."

Under the moonlight, the figures of the nine Pillars stood in the shattered courtyard. The night wind blew by, carrying the fragrance of Wisteria, as well as the Muzan chill of Muzan's presence.

Deep within the Infinity Castle, Moyu's feet landed on an upside-down wooden corridor.

All around was an infinitely extending space, with countless doors opening and closing, staircases spiraling, and lanterns floating in the void. There was no sky, no ground, only endless, chaotic architectural structures.

The six eyes' perception spread out like mercury spilling onto the ground.

He saw the entire city, or at least the entirety of it within his perception. He also saw, in a distant room, Muzan body frantically regenerating, the four potions raging within him, making the regeneration process painful and slow.

He also saw the heart of the city.

A female ghost dressed in a kimono, holding a biwa (a traditional Chinese stringed instrument), with long hair covering half her face, is sitting on a high platform. Her fingers gently brush across the strings.

Nakime.

The controller of this Infinity Castle.