Muzan Kibutsuji's figure had just dashed out of Kars's line of sight when he plunged headfirst into a domain that seared his very soul.
Endless flames.
Boundless light.
There was only a terrifying, absolute heat, pure enough to strip all matter of its original form.
All the moisture within the Infinity Castle evaporated in that instant. The twisted architecture cracked, collapsed, and finally crumbled into ash from the sudden dehydration.
Directly in front of him stood Kyojuro Rengoku, quietly holding a scorching blade forged entirely from solidified flames.
His golden-red eyes burned with a radiance akin to the core of the sun.
He slowly declared, "Bankai—[Zanka no Tachi]!"
In that split second, Kyojuro Rengoku transformed into a walking sun.
His mere existence was enough to incinerate all things.
Muzan could not even let out a scream. His body, which he boasted as the Ultimate Being, was completely vaporized by the terrifying, soul-evaporating heat of [Zanka no Tachi]. Not a single cell remained.
However.
High above, Ian's fingers snapped lightly once more.
Time rewound.
Muzan Kibutsuji's body reformed amidst endless memories of agony.
The excruciating pain of his soul being scorched by the true fire of the sun nearly drove him mad. Not daring to hesitate for even a fraction of a second, he chose a different escape route.
This time, the one blocking his path was the Stone Hashira, Gyomei Himejima.
Facing the hysterical, maddened flurry of Muzan's hundreds of bone whips, Gyomei Himejima tossed aside his flail.
Then, he slowly raised his fist.
Thud! Thud! Thud!
Muzan's bone whips smashed against Gyomei Himejima's smooth, shiny bald head like a torrential storm.
Yet, it was like raindrops striking diamond; they produced a crisp sound before instantly shattering.
Gyomei Himejima remained completely unscathed.
Tears of profound compassion streamed down his face as he spoke in a flat tone.
"This is the secret art Saitama-sensei taught me, the method to surpass one's limits and break the limiter..."
He slowly drew his fist back to his waist. His entire aura underwent an earth-shattering transformation in an instant.
He was no longer a mere rock, but a meteor capable of destroying a planet!
"Serious Series—"
"Serious Punch."
BOOM!!!
The terrifying fist pierced through everything with absolute, unreasonable force.
Not only did it obliterate Muzan Kibutsuji and all his cells into the most fundamental, unregenerable particles.
It unstoppably shattered the spatial barrier of the Infinity Castle!
In this twisted alternate dimension, it forcibly punched out a massive hole leading to the real world, revealing the azure sky beyond!
Muzan was resurrected by Ian once again.
Like a madman, he switched his escape route yet again.
Then, he crashed head-on into the Love Hashira, Mitsuri Kanroji.
At this moment, the Love Hashira's signature pink hair had been mostly dyed a violent green, reminiscent of the legendary Super Saiyans.
Her entire body radiated a pink-and-green aura filled with love and wildness, causing the very air around her to boil.
Facing the fleeing Muzan, she cupped her hands at her waist, striking a rather peculiar pose, and shouted with all her might.
"HA-ME-HA-ME-HA!"
An incredibly thick, massive pillar of energy completely swallowed Muzan.
Along with a large swath of the already dilapidated buildings behind him, he was reduced to nothingness.
Next, Muzan Kibutsuji plunged into a true, never-ending hell of despair.
He respawned.
Then, Muichiro Tokito, using those Migeika Eyes that saw through the fundamental truths of the world, instantly unleashed an optimized technique that fused Sun Breathing and Moon Breathing.
With a single move, "World-Splitting Creation: Sun and Moon's Radiance," Muzan was slashed into eighteen thousand pieces.
After that, he respawned again.
Then he saw Sanemi Shinazugawa transform into a Magical Boy with an incredibly shameful pose, before using an Arrow of Judgment made of wind elements to firmly nail him to the wall of the Infinity Castle, draining his soul as he wailed in agony.
He respawned once more.
This time, he saw Zenitsu Agatsuma standing in mid-air. Above Zenitsu's head, a ferocious, sky-blotting behemoth formed entirely of pure lightning had gathered at some unknown point.
"Lightning Release: Kirin!"
With a loud shout from Zenitsu, the lightning behemoth roared and descended from the heavens, blasting Muzan and thousands of meters of architecture beneath his feet into charred cinders.
Sasuke was dumbfounded. 'Isn't that my jutsu?'
In the distance, the First Hokage, Hashirama Senju, found himself finally witnessing a battle he could understand the roots of, and he couldn't help but excitedly offer his commentary.
He muttered to himself, "Are the young people nowadays... are they all this incredible? It seems I really am getting old."
"Naruto, I feel like there's... no real need for us to step in anymore..."
Whether it was his hundredth or thousandth resurrection.
Muzan Kibutsuji's body reformed once again.
But this time, he didn't run away.
He didn't even show a look of fear.
He just stood there quietly, his eyes hollow, drained of all color and light.
His former arrogance as the progenitor of demons, his fury toward the Demon Slayer Corps, and his millennium-spanning desire for eternal life had all been completely ground to dust through those countless, unreasonable, and wildly varied deaths.
He looked at the group before him—beings he could no longer even call human, but rather monsters.
He looked at the bizarre, incomprehensible weapons and powers in their hands.
Thud.
Muzan Kibutsuji, the King of Demons, dropped to both knees without the slightest hesitation.
With a trembling voice thick with sobs, he directed the most sincere and final plea of his thousand-year demonic life toward the bugs of the Demon Slayer Corps he had once despised the most.
"I beg you..."
"Kill me. Please, just put me out of my misery..."
Faced with Muzan Kibutsuji's sudden begging, the members of the Demon Slayer Corps were momentarily bewildered.
'What kind of trick is this guy playing now?'
Only Tanjiro Kamado, looking into those hollow eyes and hearing that desperate sobbing, sensed a trace of... a genuine yearning for release.
He slowly tightened his grip on his Nichirin Sword.
A gentle, golden flame, brimming with compassion and warmth, ignited along the blade.
Step by step, he walked toward the King of Demons, who was kneeling on the ground, having surrendered all resistance.
"Sun Breathing: Dance."
The gentle blade, as warm as the sun, carried the mercy of absolute liberation as it lightly sliced through Muzan Kibutsuji's neck.
This time, there was no pain, no scorching agony.
A serene smile of profound relief even appeared on Muzan's face.
Amidst the golden flames, his body dissolved into motes of light and completely faded away.