Don't Think a Flimsy Word Like "Genius" Can Sum Up Everything I Am!

"Fuu~"

The faint hum sounded especially clear in the silence.

Inside the spacious dojo, Kashu lightly pinched Fou with his fingertips and pressed the restless creature back into his collar.

He raised his eyes slightly, his sharp gaze piercing through the half-open wooden door and landing precisely on the uninvited figure.

"You finally came."

The newcomer wore an expensive purple robe patterned with snakes, his dark-red high ponytail meticulously tied.

Six eyes glimmered with an inhuman, ghostly light, while the katana at his waist, embedded with eyeballs, radiated an ominous aura.

Kashu had not cared which insignificant fish had blocked his path, but the instant he saw the newcomer's face clearly, his eyes narrowed dangerously.

"That appearance—you're Michikatsu Tsugikuni?"

Kashu's voice was quiet, yet carried a note of certainty.

He had once caught a glimpse of the legendary Yoriichi Tsugikuni in the Ubuyashiki clan's secret records.

Naturally, he had also heard of Yoriichi's twin brother, whose fate had become entangled with his own—later known as Kokushibo.

He had created Moon Breathing himself, awakened a Demon Slayer Mark, then betrayed his master out of fear of death, personally slew his benefactor, invited demons into the house, and ultimately became a demon, holding the position of Upper Rank One for centuries.

On the other side.

Upon hearing that nearly forgotten name, an imperceptible flicker passed through Kokushibo's six eyes before they swiftly returned to their ancient-well stillness.

He slowly walked to the center of the dojo and stopped.

"After so many years, someone still remembers that name. Even I have nearly forgotten it."

His voice was low and devoid of emotion.

A cold curve touched Kashu's lips as he mocked, "That past of murdering your master for glory probably isn't worth reminiscing about, is it?"

Before his words had faded, killing intent arrived!

Moon Breathing: Fifth Form: Moon Spirit Calamitous Vortex!

Kokushibo did not move, nor did he draw his sword, yet crescent-shaped sword energy exploded out of thin air, erupting around him!

Rather than retreat, Kashu charged forward, his sword force roaring like a raging sea!

Water Form: Raging Scales!

The moonlight crashed into a boundless deep sea, stirring up towering waves as chilling sword light surged back!

When the strike failed, a cold glint flashed through Kokushibo's six eyes. He drew his blade with lightning speed.

The blade flashed like a black ribbon, using the First Form to precisely intercept every retaliatory streak of sword light.

Kashu pressed in with the momentum, his platinum longsword clashing violently with Kokushibo's Sword, which was covered in eyeballs. Blinding sparks burst forth, and the clang of metal was deafening!

"So that's Moon Breathing. You've also opened the Transparent World, haven't you?"

There was a trace of understanding in Kashu's tone.

Kokushibo remained silent, only feeling the force coming through his arm grow heavier with each successive wave, as weighty as a mountain.

He immediately pushed off with his feet and retreated swiftly. At the same time, he twisted his wrist and raised his sword to counterattack!

Moon Breathing: Second Form: Pearl Flower Moonplay!

In an instant, countless high-speed slashes tore through the air, bringing with them even more chilling moon blades that shot toward Kashu in an overwhelming fan-shaped barrage!

Relying on his extraordinary perception and swift footwork, Kashu darted and twisted through the gaps between the impenetrable moon blades, his figure elusive.

Yet the ground beneath his feet was shredded by invisible blade winds, leaving ravines so deep they seemed to expose bone.

It had to be said that Kokushibo's swordsmanship, infused with Blood Demon Art, was far stranger and harder to guard against than ordinary sword techniques.

Kashu had to watch not only Kokushibo's Sword itself, but also the erratic, unpredictable moon blades that emerged with every slash.

Kokushibo himself, on the other hand, had no such concerns.

Even when moon blades occasionally carved slender wounds across his body and crimson flesh rolled open, he regenerated completely in the blink of an eye.

"Though this isn't my first time seeing it, I still have to say—"

Kashu abruptly halted, the platinum longsword held in reverse humming.

He suddenly exerted force beneath his feet. The hard floor exploded, and his entire body shot forward like a white bolt of lightning!

"Your demon regeneration is way too unfair!"

His heavy slash bore the force of thunder, crashing down like a giant beast swinging its tail!

Kokushibo's Sword instantly proliferated more twisted blades as Kokushibo counterattacked with all his strength!

Moon Breathing: Eighth Form: Moon Dragon Ringtail!

Boom—!

The two peerless weapons collided explosively, and a terrifying shockwave spread madly outward from the pair.

The surrounding moon blades were all blown apart, while spiderweb-like cracks spread across the floor!

The gale howled, making both their clothes flap wildly.

Kokushibo's six eyes stared fixedly at the human before him, cold light blazing within them.

To be honest, he had never truly regarded Kashu as a threat before this, even knowing that Kashu had slain Akaza and Gyokko.

After all, he had opened the Transparent World, possessed a Demon Slayer Mark, and had the powerful physique demons possessed far beyond humans.

Who could have expected him to be evenly matched against a mere human?

Just as Kokushibo's mind trembled and he silently wavered in disbelief.

Kashu took a deep breath and carefully recalled every attack his opponent had made.

The aura around him and the rhythm of his breathing began to change in subtle yet profound ways.

Dragon Breathing: Moon Form: Dark Claw!

In a daze, Kokushibo saw five incomparably condensed, razor-sharp black claw shadows appear in his vision.

They tore through the sky and descended from above, like a giant dragon extending its claws to crush the insect beneath its feet into dust!

His face changed in horror. He raised Kokushibo's Sword with all his strength to block, but—

Crack!

Man and sword shattered together!

Imitation Celestial Body: Black Hole.

Before Kokushibo's shattered flesh could regenerate, a terrifying force of attraction descended upon him, making his heart quiver.

A dark technique had already formed in Kashu's palm, instantly pinning him firmly to the ground!

"How does it feel? Losing to the style you created yourself. Satisfied?"

Kashu looked down at him, his voice cold.

Kokushibo, struggling to writhe on the ground, had all six demonic eyes contract violently from extreme pain and unwillingness.

When he looked at Kashu again, his gaze finally held genuine jealousy and hatred.

"Replicating an enemy's techniques specifically to defeat them—what arrogance!"

He howled, his voice twisted and shrill.

"You too! Him too! All you so-called geniuses!"

"You who have never truly worked hard! How could you possibly understand? How could you understand the helplessness and despair of training desperately no matter what, yet never being able to reach your goal!"

"Genius? Never worked hard?"

Kashu let out a low laugh, icy crystals mixed within it, filled with endless mockery.

Countless scenes soaked in blood and despair flashed through the depths of his eyes—

Cold, piercing stares, endless experiments, bloodstained metal tables, and day after day of combat tests struggling at the edge of life and death...

"Don't think a flimsy word like 'genius' can sum up everything I am!"

The instant his words fell, he raised a hand and dispersed the technique binding Kokushibo, lowering his body slightly.

An indescribably scorching energy that made one's heart quiver began to spread madly throughout the dojo.

"What!?"

Kokushibo, who had just regenerated and was struggling to rise, underwent a drastic change in expression. His pupils shrank to pinpoints!

At that moment, the figure reflected in his eyes was one he could never forget, and terror flooded over him like a tide.

His younger twin brother, whom he had spent his entire life unable to catch up to by even the slightest margin!

"You... just who are you..."

Dragon Breathing: Sun Form: Red Dragon!

A savage giant dragon formed entirely of pure flames roared forth. Its jaws opened wide, instantly swallowing the horrified Kokushibo and crushing him to pieces!

The enormous dragon twisted wildly through the air, baring fangs and claws, spreading its wings and swinging its tail as its roar shook the heavens!

The temperature rose steadily. The dojo's wooden structure and furnishings burst into flame without fire, and the spreading blaze turned the place into a raging inferno in the blink of an eye.

The giant dragon shuddered, its radiance fading to reveal Kashu's figure. His robes fluttered around him, making him seem like a god.

"Letting a traitor who murdered his master die beneath Yoriichi Tsugikuni's style can be considered an end to the centuries-long grievance between you brothers."

As Kashu continued onward into the deeper reaches of Infinity Castle.

The Kasugai Crows that had been lurking throughout the battlefield and secretly observing every fight suddenly spread their wings and flew high, as if receiving a unified command. Their hoarse cries tore through the sky.

"Good news! Good news!"

"The Commander-in-Chief has slain Upper Rank One!"

"The Commander-in-Chief has slain Upper Rank One!"

The news of the first victory spread like wildfire, instantly reaching the ears of the Demon Slayer Corps members still fighting in blood.

A gap was torn through the shadow of despair, and the light of hope illuminated their weary yet resolute faces!

Their morale soared!

Fighting spirit reignited in the eyes of every swordsman. They became more cautious, yet also more focused as they battled the demons before them.

Even the most troublesome Upper Rank One had already been slain by the Commander-in-Chief. The ones they were assigned to were merely insignificant fish—could they not even manage something as simple as buying time!?

They absolutely could not lose!

They absolutely could not die here!

They had to give everything they had and hold on!

As long as they could endure until the Commander-in-Chief's final battle against Muzan Kibutsuji, it would be the Demon Slayer Corps'—the victory of all their fallen comrades'—

Complete victory!

Yet just as the good news swept across the battlefield.

In the deepest part of Infinity Castle.

Within those crimson eyes that overlooked everything, there was not the slightest ripple—only chilling calmness, and a trace of... amusement?

"Oh? Michikatsu Tsugikuni... is dead too? What a... boring piece of trash."

A low voice, halting yet magnetic, drifted through the vast, deathly silence of the darkness, carrying a nearly imperceptible... anticipation?

"Then... it is time for the 'real game'... to begin."