Kibutsuji Muzan — a being who fancied himself nearly perfect, a vengeful Demon progenitor who styled himself a natural disaster — felt, for the first time in his existence, the unmistakable scent of death.
He feared death above all else.
For five hundred years, everything he had done — splitting his flesh, creating vengeful Demons, concealing his movements, hiding beneath the wings of great yokai — had all been in service of not dying.
But today was different.
He knew that if he didn't act now, once every one of his backups was wiped out, he would truly, completely, irreversibly die.
No one would help him.
Though he sheltered beneath Hagoromo-Gitsune, he was in truth only a minor subordinate under Kidomaru, who himself served beneath Hagoromo-Gitsune.
With no yokai power and no spiritual power to draw on,
the forces stationed in Kyoto wouldn't even bother to intervene — they would simply write it off as an especially common case of infighting among humans.
That, in fact, was precisely what Kobe Hikaru had calculated.
Rather than call on the strength of yokai or even priestesses and mages, he had used something exceedingly rare instead — human power!
Kibutsuji Muzan had truly never encountered a situation like this before.
He had always believed himself hidden flawlessly.
Those who knew of his existence and also knew his weakness to sunlight were vanishingly few.
Those who knew of his sunlight weakness and also knew he had split his body in advance — in this entire world, there was almost no one.
Even to deduce it required an exhaustive understanding of him.
And even if someone did deduce it, those capable of effectively acting on that knowledge were still vanishingly few.
The probability was near zero.
Muzan never gave any being the chance to reach that probability.
Yet the yokai standing before him seemed to be the exception — he could sense that this creature truly understood him.
The unknown, compounded with death.
Fear peaked in an instant, then flipped, in the same breath, into fury.
"Very well, then—"
Muzan's slit pupils turned crimson to the utmost extreme.
Dozens of his split bodies, pinned across the wilderness by the Earth Barrier, moved at once.
Heedless of everything.
Purplish-black flesh and blood burst from the surface of every split body, turning into a viscous liquid that surged across the ground, crossing through the barrier's light.
Even as it burned, it did not stop — it converged toward the center.
Bones fractured and reassembled within the liquid; organs crushed together and regenerated in the fusion.
The total mass, the total blood, the total life force of dozens of bodies condensed, in an astonishingly short span, into a single whole.
The ground caved in beneath it.
A colossal figure rose out of the whirlpool of flesh and blood.
It stood over a hundred feet tall.
Its whole body was purplish-black, muscle fibers twisted and interwoven, with countless tentacles extending from every part of its torso — each one thick enough to embrace with both arms, each tip splitting into bone spikes, claws, even human faces.
Five heads were arrayed at its crown, each bearing Muzan's own face, yet each twisted into a different expression — rage, terror, greed, hatred, madness.
Seven hearts beat in unison within a purplish-black chest visible through the skin, producing a dull, thudding rhythm.
This was the complete, ultimate form never shown in the original — one unmarred for centuries by any wound Tsugikuni Yoriichi had ever inflicted.
Kibutsuji Muzan had recalled all the power scattered around him, compressed it, and smelted it into a combat body that exceeded every previous limit.
And what came next—
was Blood Demon Art.
In the centuries before this, the lesser and even the high-ranking vengeful Demons Muzan had created were never granted this ability — there had been no need. In that earlier age, even Demon Slayers armed with Sun Blades posed him no real threat, so the Demons he made only needed basic regeneration and strength.
Only recently had Muzan begun granting Demons Blood Demon Arts.
On that same foundation, Muzan himself, as the source of all demon blood, naturally commanded multiple Blood Demon Arts of his own.
Five hundred years of accumulation — dozens of Blood Demon Arts bloomed at once.
Purplish-black blood sprayed from the tentacle tips, turning to corrosive acid mist in the air — grass and leaves within dozens of yards withered and charred instantly.
Blood spikes burst up from the ground, forming a forest-like array of thorns.
Slabs of flesh peeled from the torso, transforming into moving barriers that carved the entire battlefield into a maze.
Tentacles wrapped in blood swept through the air, each lash gouging trenches several yards deep into the earth.
The wilderness for dozens of yards around was, in an instant, rendered into a scene of hell.
Witnessing all this, Tsugikuni Yoriichi's expression turned severe, and he stepped forward.
Golden heat mist rose from his body in the fully concentrated state of the Breath of the Sun, the crimson Sun Blade held level before him — his Transparent World had already mapped out every tentacle, every heart, every brain of that colossal monstrosity.
A creature like this was terrifying.
But he could cut it down.
He would only need time.
And yet—
he had not even taken his first step.
The air before him was already torn apart.
It was Kobe Hikaru.
The bone-and-thunder colossus of his Asura Mutation leapt forward before him — its six-meter frame was less than half the size of the Demon King's fully transformed hundred-foot body, but the yokai aura amplification from the resonance of his twin organs had already reached its peak in that instant.
The dual circulation of fire and water had once again formed a two-way current within the Asura Mutation—
and to that, he added the Demon's Breath.
Though he still lacked lungs.
The Asura's Lung had not yet taken shape. The Demon's Breath had been comprehended, but there was no organ to house that circulation — like possessing the technique of breathing without a vessel to breathe with.
But Kobe Hikaru used another method.
He forced the Demon's Breath to run inside the chest cavity of the Asura Mutation — not through lungs, but using yokai aura itself as the medium, pouring the turbid qi of heaven and earth directly into the gaps of the bone-thunder frame.
It was crude.
No refinement, no filtering, no lungs to serve as a furnace for purification — just the turbid qi, wrapped in yokai aura, forced wholesale into every groove of the bone-thunder colossus.
It was an extremely forced method.
Low efficiency, heavy loss, a load far beyond the norm — but layered atop the dual-organ circulation, this crude infusion of Demon's Breath still managed to forcibly drag up the Asura Mutation's actual output.
The yokai aura amplification, stacked on top of the Nine Mutations,
broke through to a level comparable to an extremely high-ranked yokai at the Eleventh Transformation stage.
This was the limit he could currently reach.
But that limit, against this hollow, showy ultimate form of the Demon King, was more than sufficient.
The Blood-Fire Mutation erupted from the Heart of Asura, dark red yokai fire spreading along the bone frame.
At the same time, the Yomi qi forcibly driven by the Demon's Breath seeped out from the gaps in the bone frame — that freezing, annihilating force, as if drawn straight from the underworld, truly clung to the blade's edge.
Dark red and Yomi's darkness intertwined, coiled together, compressed—
Sun and Demon — or rather, a union of yin and yang.
An imperfect union of yin and yang.
The sun's burning and Yomi's annihilation layered on the same cutting edge — the former burning flesh and blood to nothing, the latter denying regeneration outright.
Though, lacking the refinement of true lungs, the Yomi power was only three or four tenths of the theoretical complete form Kobe Hikaru had calculated in his own projections, the sun's burning power was at full strength.
Against a Kibutsuji Muzan who had scattered his power across the entire land and hastily patched himself back together—
three or four tenths of Yomi's power plus full-strength sunlight was more than enough.
And so, at this moment.
Onikiri and Yomikiri were both projected and enlarged from the giant hand of the Asura Mutation, colors never seen before surfacing along their edges.
Half was the dark red fire of the blazing sun; half was the dim, spectral bloom of Yomi.
Where the two lights intertwined, the very air evaporated, leaving behind a visible rift of vacuum.
But in truth, it was only a single strike.
A simple, vertical cleave.
From dead center of the five heads atop Kibutsuji Muzan's hundred-foot frame — straight down, all the way to the soles of its feet.
Muzan's ultimate form never even had time to complete a second wave of Blood Demon Art release.
That single stroke of intertwined sun-and-demon light split the entire colossal body clean down the middle, the cut surfaces scorched by blazing sun fire and annihilated by Yomi's power in the same instant — the starting point of regeneration collapsed utterly under the pincer of both forces.
All seven hearts were pierced through by that single strike.
All five heads were cleaved apart in that same instant.
Kibutsuji Muzan shrieked in terror, wailed, roared in mad fury — but it seemed to make no difference.
The hundred-foot body of the Demon King, the instant the blade-light faded, began to char, crumble, and scatter to ash from the cut surface outward.
Muzan's howling lasted less than two seconds before it cut off.
Nothing remained but ash.
Ash filling the sky.
The Asura Mutation folded inward, the bone-and-thunder colossus crumbling apart, and Kobe Hikaru dropped back to the ground.
He shook his slightly numb right hand—
his entire right arm, from shoulder to fingertip, trembled, and fine cracks had appeared across the bone frame.
Without the buffering refinement of an Asura's Lung, the strain of forcing the turbid qi of the Demon's Breath directly into his bone frame had cost him more than he'd expected.
This one strike had pushed him past his limit.
But the outcome was already sealed.
Yoriichi stood behind him, the Sun Blade still raised halfway, golden heat mist slowly dissipating in the night wind.
He'd had no chance to strike — and no longer needed one.
He watched the ash drifting down from the sky, an indescribable look in those deep crimson eyes.
It looked like astonishment.
And also, somehow, like relief.
Kobe Hikaru glanced back at him.
"All that flashy nonsense, and I just ended it in one shot."
So he said, plain and simple.
Yoriichi was silent for a moment.
"...Yeah."
The reason for it was actually quite simple.
Kibutsuji Muzan's power had never been weak — five centuries of accumulated demonic strength was enough to make any being wary of him. Even if it fell short of great-yokai level, its total sum came close to what an ordinary high-ranking yokai possessed in yokai aura.
But that was exactly where his problem lay — he was spread too thin.
The flesh and blood he'd split off covered the entire land; the Demons he'd created were scattered everywhere.
It looked like an inexhaustible supply of reserves, but in truth, every fragment diluted his overall strength.
When he was forced to draw all that power back into one body, the actual density of that ultimate form was nowhere near that of a yokai who had genuinely accumulated an equal total of yokai aura through the proper path to the twelve-mutation stage.
It didn't even match an Eleventh Transformation yokai.
Large in form, but thin in substance.
Dozens of Blood Demon Arts unleashed at once looked terrifying, but the power allotted to each was, in truth, unimpressive.
Faced with a fighting style that compressed two mutually countering forces into a single strike — faced with someone like Kobe Hikaru, a demon among yokai who concentrated a multitude of abilities into himself—
it really did come down to just one cut.
Of course, that was only possible given that Kikyo's Earth Barrier had locked down his backups, the Demon Slayer Corps had wiped out his flesh scattered across the land, and Tsugikuni Yoriichi had forced him to reveal himself.
Remove any single one of those links, and it would have been impossible to kill Kibutsuji Muzan completely.
But all those links, from beginning to end, had been laid out on Kobe Hikaru's own chessboard.
In this way—
he could finally ensure there would be no future troubles at all.
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