Anime Crossover: Oni Samurai Artifact System — Chapter 203

Chapter 203: All Flash, Insta-Killed

Kibutsuji Muzan—the creature who claimed to be infinitely close to perfection, the progenitor of demons who styled himself as a walking natural disaster—felt the icy breath of death for the very first time.

He feared death above all else.

For five hundred years, every action he took—splitting his flesh, manufacturing lesser demons, erasing his tracks, and groveling under the command of a Great Yokai—was solely to secure his own immortality.

But today was different.

He knew with absolute certainty that if he did not move now, once all his backup vessels were purged from the earth, he would truly, completely, and irreversibly die.

No one was coming to save him.

Although he had hidden himself under the banner of Hagoromo Gitsune, he was nothing more than a minor demonic subordinate answering to Kidomaru, who in turn answered to the Great Yokai herself. Muzan lacked true Yokai Energy and spiritual power. The elite subordinates in Kyoto would not spare a single glance for his plight; they would merely view this as an exceedingly common internal squabble among humans.

This isolation was exactly what Kobe Hikaru had calculated.

Hikaru had not relied on the sweeping forces of great yokai, nor had he called upon high-ranking priestesses and mages. He had cornered the Demon King using only an extremely specialized, entirely human force.

Muzan had truly never encountered a situation like this. He had always believed his concealment was flawless. Those who knew of his existence and his fatal weakness to the sun were incredibly few. Those who knew of his solar vulnerability and also knew he had preemptively split his body into hidden fragments were practically non-existent.

Even if someone managed to deduce his secrets, they would require a complete understanding of his entire biological makeup. And even if they possessed that knowledge, the individuals capable of effectively acting on it could be counted on one hand.

The probability of his demise was supposed to be zero. Muzan would never willingly give any living creature such an opportunity.

Yet the undead samurai standing before him was an anomaly. Muzan could feel it in his very marrow; this opponent truly understood him inside and out.

The terror of the unknown, violently clashing with the absolute certainty of his impending death, pushed Muzan’s fear to its absolute peak. A second later, that suffocating terror inverted into pure, unadulterated rage.

“In that case—”

Muzan’s slit pupils contracted, bleeding into a deep, extreme shade of crimson.

Dozens of his flesh clones, currently pinned to the wilderness dirt by Kikyo’s Earth Barrier, moved in terrifying unison.

They acted with complete reckless abandon.

Purple-black flesh violently ruptured from the surface of every single clone, melting into a viscous, bubbling liquid. This foul sludge dragged itself across the glowing purification light on the ground, refusing to stop even as it was actively burned and scorched, converging rapidly toward a single center point.

Bones audibly snapped and rearranged within the shifting liquid pool. Organs were brutally crushed into paste and rapidly regenerated during the violent fusion process. The entire mass, containing all the blood and life force of dozens of bodies, condensed into a single grotesque whole in a matter of seconds.

The ground groaned and collapsed under the sudden, immense weight.

A colossal figure rose from the swirling vortex of flesh.

It towered over thirty meters tall. Its entire body was a sickly purple-black, with thick muscle fibers twisted and braided together like steel cables. Countless tentacles violently erupted from various points on its massive torso. Each appendage was as thick as a grown man’s torso, branching out at the ends into jagged bone spikes, razor-sharp claws, and agonizingly stretched human faces.

Five distinct heads sprouted from the top of the monstrosity. Each head bore Muzan’s face, yet each was contorted into a radically different expression—anger, fear, greed, hatred, and pure madness.

Seven distinct hearts beat simultaneously within the exposed, translucent purple-black chest cavity, emitting a dull, rhythmic thumping that shook the surrounding air.

This was his complete, ultimate form. It was a state of being he had never been forced to reveal, a form entirely untouched by the lingering, burning scars left by Tsugikuni Yoriichi hundreds of years ago. Muzan had forcibly recalled all his scattered power, compressing and smelting it into a combat body that shattered his previous limits.

What followed was the absolute pinnacle of his Blood Demon Art.

In the centuries prior, the lower and even upper-rank demons Muzan created had never been granted this specific ability, simply because it was unnecessary. Even if the Demon Slayer Corps of this era wielded their Nichirin Blades, they posed zero threat to him. The demons he engineered only required basic regeneration and brute strength to slaughter humans.

Only recently had Muzan begun distributing Blood Demon Arts to his creations. As the absolute source of all demon blood, Muzan himself naturally commanded multiple, devastating Blood Demon Arts.

Fueled by five hundred years of accumulated malice, dozens of Blood Demon Arts bloomed across the battlefield simultaneously.

Purple-black blood sprayed from the tips of the flailing tentacles, instantly vaporizing into a highly corrosive acid mist. The grass, leaves, and trees within a hundred-meter radius instantly withered, turning to black ash.

Massive bone spikes erupted from the earth, forming a dense, deadly forest of jagged spears. Walls of pulsating flesh detached from his main torso, transforming into moving, fleshy barriers that partitioned the entire battlefield into a grotesque maze. Tentacles whipped through the air, trailing toxic blood, each lash carving trenches several meters deep into the solid ground.

The surrounding wilderness was instantly transformed into a literal purgatory.

Witnessing this apocalyptic display, Yoriichi’s expression turned entirely stern. He stepped forward, his grip tightening on his hilt.

Golden heat mist, a byproduct of the absolute full-focus state of Sun Breathing, began to steam from his skin. He held his crimson Nichirin Blade horizontally before his chest. Through the Transparent World, his eyes had already mapped the exact position of every flailing tentacle, every beating heart, and every frantic brain hidden within that colossal monster.

The beast was undeniably terrifying.

But he could cut it. It would merely take a little time.

However, before Yoriichi could even initiate his first step, the air directly in front of him was violently torn apart.

It was Hikaru.

The Bone-Thunder Giant of the Asura Transformation leaped forward, interposing itself between the swordsman and the Demon King. The six-meter-tall skeletal avatar was less than a fraction of the size of Muzan’s thirty-meter-tall ultimate form, but the Yokai Energy amplification generated by the resonance of Hikaru’s two demonic organs had already reached its absolute zenith.

The dual cycle of fire and water formed a rapid, back-and-forth circuit within the Asura Transformation, heavily augmented by Demon Breathing.

He still lacked proper lungs. The Asura Lungs had not yet formed within his undead body. Although he had comprehended the technique of Demon Breathing, he possessed no physical organ to properly carry and regulate that cycle. It was akin to mastering the theory of breathing while lacking the vessel to actually draw breath.

But Hikaru was nothing if not pragmatic. He simply used another, far more brutal method.

He forcibly operated Demon Breathing directly within the hollow chest cavity of the Asura Transformation. Instead of using lungs, he used his own Yokai Energy as a raw medium, violently dragging the turbid energy of heaven and earth straight into the microscopic crevices of the Asura Transformation’s skeletal frame.

It was an act of pure violence against his own body.

Without refinement, without filtration, without lungs acting as a furnace to purify the intake, he simply crammed the raw, toxic turbid energy, wrapped tightly in his own Yokai Energy, into every single groove and crack of the Bone-Thunder Giant.

It was an extremely forced, highly damaging approach. The energy efficiency was abysmal, the physical recoil was massive, and the load placed on his skeletal structure far exceeded its natural limits. But by violently superimposing this crude infusion of Demon Breathing onto his existing two-organ cycle, the actual damage output of the Asura Transformation was forcibly dragged upward.

The Yokai Energy amplification, stacked on top of his Ninth Transformation base, violently broke through to a tier comparable to a high-level demon of the Eleven Transformations.

This was the absolute limit of his current power.

However, this limit was more than enough to face the ultimate form of the Demon King thrashing before him—a form that was entirely all show and no substance.

The Blood-Fire Transformation erupted from the Asura Heart. Dark red demonic fire rapidly spread along the giant skeletal frame, igniting the bones.

Simultaneously, the power of The Underworld, forcibly driven by his crude Demon Breathing, began to seep out from the crevices of the skeleton. That freezing, absolute annihilating power from the world of the dead clung tightly to his massive blades.

Dark red flames and the freezing power of The Underworld intertwined, violently entangling and compressing against each other. It was a clash of Sun and Demon, a forced, imperfect unity of Yin and Yang.

The burning heat of the sun and the absolute annihilation of The Underworld were superimposed onto the exact same blade edge. The former existed to burn away flesh; the latter existed to completely negate regeneration.

Because he lacked the essence of true lungs, the Underworld power he could manifest was only a mere three or four percent of the theoretical complete form he had calculated. However, the burning power of the sun was operating at maximum capacity.

Against a Kibutsuji Muzan who had spent centuries scattering his power across the globe, only to hastily piece it back together in a panic, three percent of The Underworld combined with full-capacity sunlight was more than enough.

And so, he struck.

The massive blades, Onikiri and Yomikiri, were simultaneously projected and enlarged from the giant skeletal palms of the Asura Transformation. Colors never before seen in this world emerged along the cutting edges.

One half of the blade arc was the dark, roaring red fire of the scorching sun. The other half was the dim, light-swallowing brilliance of The Underworld.

Where the two conflicting lights intertwined, the very air evaporated, leaving behind a visible, distorted vacuum fissure in space.

It looked like a complex technique, but it was actually just a single strike.

Just a simple, brutally heavy vertical slash.

The blade light started from the very center of the five heads atop Muzan’s thirty-meter-tall body, tearing downward, cleanly splitting the air all the way to the soles of his monstrous feet.

Muzan’s ultimate form did not even have the time to complete the release of his second wave of Blood Demon Arts.

That single blade light, perfectly intertwining solar fire and underworld annihilation, cleaved the entire giant body perfectly in half down the center. The massive cross-section of the wound was simultaneously scorched to ash by the sun fire and erased from existence by the power of The Underworld. The very biological starting point of Muzan’s regeneration completely collapsed under the flawless pincer attack of the two opposing forces.

Seven beating hearts were pierced and destroyed by a single strike.

Five screaming heads were split open in an instant.

Muzan was terrified. He wailed, his five mouths roaring in absolute fury and despair, but the sounds meant nothing.

The exact moment the blade light dissipated into the night air, the towering Demon King’s body began to rapidly carbonize. The flesh disintegrated, turning to brittle ash that scattered wildly from the massive cut surface.

Muzan’s final, agonizing wail lasted for less than two seconds before it was abruptly silenced.

Nothing was left but ash.

Thick, gray ash filling the night sky, drifting down like dirty snow.

The Asura Transformation rapidly retracted. The massive Bone-Thunder Giant disintegrated into particles of light, and Hikaru landed heavily back on the scorched earth.

He shook his slightly numb right hand. His entire right arm was trembling uncontrollably from the shoulder down to his fingertips, and several fine, jagged cracks had appeared along his own skeletal structure.

Without the buffering essence of the Asura Lungs, the physical recoil caused by forcing the turbid energy of Demon Breathing directly into his bones was far greater than he had calculated.

That single strike had severely overdrawn his reserves.

But the outcome was already set in stone.

Yoriichi stood quietly behind him, his crimson Nichirin Blade still held halfway drawn. The golden heat mist of his breathing technique slowly dissipated into the cool night wind.

He had not found a single opening to strike, simply because a strike was no longer needed.

The legendary swordsman watched the gray ash falling all over the sky. His deep red eyes held a complex, indescribable emotion.

It looked like genuine surprise.

And, beneath that, a deep sense of relief.

Hikaru turned his head slightly, looking back at the quiet swordsman. His face remained entirely deadpan.

“All that flashy stuff, just to get insta-killed.”

Yoriichi remained silent for a long moment, watching the last of his ancient enemy blow away in the wind.

“…Hm.”

The reasoning behind the anti-climactic end was actually quite simple.

Muzan’s power was never truly weak. The sheer volume of demonic energy he had accumulated over five hundred years was enough to make any living creature wary. Even if he hadn’t quite reached the tier of a true Great Yokai, his total energy reserves were definitely close to the Yokai Energy held by an average high-level demon.

But his fatal flaw lay precisely in his paranoia. His power was far too scattered.

The flesh he had split off was spread too thin across the world, and the demons he had created to act as his shields were scattered everywhere. It gave the illusion that he had endless backup plans and infinite lives, but in reality, every single fragment he separated was actively diluting his core strength.

When he was finally forced into a corner and recalled all his power into one single body, the actual density of that massive ultimate form was pitiful. It was far inferior to a Twelve Transformations demon who had properly and densely accumulated the exact same total amount of Yokai Energy.

It wasn’t even on par with an Eleven Transformations demon.

He was massive in form, but incredibly thin in actual quality.

Dozens of Blood Demon Arts released simultaneously looked like an apocalyptic threat, but the actual power allocated to each individual attack was simply not enough to cause real harm to a prepared opponent.

Encountering a hyper-lethal fighting style that perfectly compressed two highly restrictive powers into a single, devastating strike—encountering a true anomaly among demons like Hikaru, who gathered and refined multiple abilities into one dense body—spelled his absolute end.

It truly only took a single strike.

Of course, the entire execution relied on a flawless setup. It required Kikyo’s Earth Barrier to perfectly lock down his hidden backups. It required the Demon Slayer Corps to carefully clear out the flesh fragments he had spread across the world. And it required Tsugikuni Yoriichi’s terrifying presence to force the coward out into the open.

Lacking even a single one of these crucial links, it would have been entirely impossible to completely kill Kibutsuji Muzan.

But every single one of these links, from the very beginning to the bitter end, had been carefully placed on Hikaru’s chessboard.

Because of this careful planning, the deed was finally done. The future trouble had been eliminated, forever.