The figure in the haze took a step forward—slow, deliberate, almost ceremonious. Dust curled up from the earth beneath his sandals, yet it wasn't the impact of his footfall that stirred it.
It was his presence.
Even the air recoiled.
The ground beneath him rippled—not visibly, but in sensation. The very rhythm of the world seemed to retreat as he moved, as though nature itself resisted the weight of what approached.
Another step followed.
With it, the haze began to thin. The shadow sharpened—edges once fluid now hardening into form. From the shifting mist emerged the silhouette of a long blade resting at his hip, its scabbard aged yet untouched by rust. A katana. Worn. Familiar.
His haori trailed behind him, torn by time but still clinging to its dignity. Its colors, though dulled, whispered of something once sacred. A reflection twisted by darkness. The pattern bore a resemblance—not exact, but enough. Enough to draw something raw from the past.
Yet his face remained hidden. The light bent strangely around it, refusing to give clarity. Only the shape of long hair, tied back. Only the impression of something once human.
And still, the pressure rose.
Each breath taken in his presence felt heavier, as if the lungs were reluctant to work. As if the body understood what the mind had not yet fully accepted.
Yet Yoriichi didn't move.
He didn't reach for his blade. Didn't shift his stance.
He simply stood there, rooted like a mountain in stillness. His eyes, unwavering, remained fixed on the figure with a calm that bordered on unnatural. But it wasn't born of courage or resolve. It was older than that.
It was memory.
He didn't narrow his eyes.
He didn't even blink.
Instead, his expression softened—just slightly. Something between sorrow and inevitability passed across his face, like the ghost of a storm cloud.
He exhaled, long and low. The breath carried weight, carried years.
And in a voice so quiet it nearly vanished into the wind, he spoke.
"…Brother."
Rengoku's breath caught in his chest—a sharp, involuntary pause, as if the air around him had thickened beyond tolerance. His body stiffened, not from fear, but from the sheer weight of the moment. The word "Brother," spoken by Yoriichi in a voice so calm and somber, echoed louder than any shout might have. It struck something deep within him—something ancient and unexplainable.
A chill surged down his spine, crawling beneath his skin like icy fire.
But even before that word had fully settled into the open field—before it had time to ripple across the tall grass and vanish into smoke—Rengoku already knew.
That presence.
That crushing, suffocating, almost tangible pressure.
It wasn't just power—it was hierarchy, carved into the air itself. The sheer density of demonic energy around them made the Lower Moons feel like shadows compared to this storm of presence. Rengoku's instincts screamed, his body recognizing the danger even as his mind struggled to accept it.
The figure stepped again from the mist.
And with that final stride, the haze peeled back just enough to offer clarity.
What emerged was a being both regal and monstrous—taller than most, his posture straight, his movement graceful, deliberate. Long, flowing black hair spilled past his shoulders, partially veiling the stark contrast of pale skin that shimmered with otherworldly strength. His haori, though battered and aged, held a design too familiar—its pattern echoing something Rengoku couldn't yet name.
But it was his face that stole the breath from his lungs.
Six burning eyes.
Three on each side—each one fixed forward with unnatural stillness, glowing like dying stars in a blackened sky. They weren't merely looking—they were watching, dissecting, remembering. Each blink felt centuries old.
From his waist hung a katana—simple in make, but humming with dormant menace. The blade hadn't been drawn, but its presence alone was enough to set the hairs on Rengoku's arms on edge, like a warning etched in steel.
Rengoku's eyes widened. His heart pounded harder now.
"That's…" he whispered, voice strained as if even speaking the words felt dangerous, "…Upper Moon One…"
His jaw clenched, eyes flicking between the demon and the man at his side—the swordsman who had felled Lower Moon One with a single radiant strike, who now stood unmoved before this towering storm.
From all the battles I've fought… all the demons I've faced… none of them—not one—felt like this.
This was different.
This was something else entirely.
Rengoku's breath wavered as his eyes remained fixed on the towering figure ahead. So this… this is the one who stands at the top of the demon hierarchy. The Upper Moon One. The apex. The embodiment of power sharpened over centuries. The aura rolling off him wasn't just pressure—it was domination. Cold. Absolute. Refined through blood, time, and darkness.
It's suffocating.
He clenched his fists unconsciously, but his limbs refused to respond the way they should. His legs, trained to dash into battle, now felt like they were buried knee-deep in stone. His instincts—those unshakable instincts that had carried him through countless fights—were screaming. Not to fight. Not to defend.
But to run.
He's not just an enemy.
He's the predator.
And I… I'm the prey.
The realization hit him like a blade through the chest, and it wasn't pain that froze him.
It was the truth.
My heart is pounding, but my body… it won't move.
And beside him, Yoriichi still stood in complete stillness, unfazed—as if this nightmare born of shadows was no stranger to him.
For centuries, the hierarchy of the Upper Moons had remained untouched—unchanged through the passing of generations, unshaken even as countless Demon Slayers rose and fell. Unlike the ever-shifting ranks of the Lower Moons, the Upper Ranks stood immovable, like carved stone beneath the shadow of Muzan Kibutsuji's throne. Their power was immense, their potential terrifying—each one handpicked by Muzan himself, chosen not just for strength, but for a deeper resonance with his dark will.
But even among the Upper Ranks, there existed a difference—one so vast it could scarcely be bridged.
Upper Moon Two, though fearsome in his own right, stood at a distance… a shadow cast by a greater force. Because the power held by Upper Moon One was not just superior—it was definitive. He was not merely first by number. He was first by dominion. By terror. By legacy.
The gap between them was a chasm.
A reminder that at the very peak of demonkind's hierarchy stood a being whose strength neared that of Muzan himself—one whose presence alone could silence a battlefield before a blade was even drawn.
And now, the most powerful demon in that dreaded hierarchy stood before them.
Not a memory.
Not a rumor whispered by terrified survivors.
But real—breathing, watching.
Right there in front of Rengoku and Yoriichi.
The air around them felt heavier, as if the weight of centuries had settled into that single moment. The wind itself seemed to falter, uncertain whether to move forward or retreat. Kokushibo—the one who had held the rank of Upper Moon One longer than any slayer had held breath—stood still, yet his presence moved like a tide. Overwhelming. Crushing.
Yoriichi remained unmoved, calm as stone.
Rengoku stood beside him, fire behind his eyes, yet even the Flame Hashira felt the crackle of unease ripple through his spine. He had faced demons before—dozens, maybe hundreds—but never like this. Never one that made the night itself seem to hold its breath.
From within the veil of shadows, Kokushibo narrowed his eyes—six in total, glowing faintly like coals in dying fire. Each one locked onto the silhouette in the distance with silent, piercing intensity. The wind stirred around him, yet he remained utterly still, as though even motion might betray his composure.
Then, Transparent World.
The realm beyond sight unfolded before him.
Veins pulsed with unmistakable clarity. Muscles contracted and relaxed in perfect sequence. The rhythm of life, once hidden beneath skin and shadow, now revealed itself in exquisite detail—fluid, natural, and terrifyingly familiar.
He saw it all.
The steady heartbeat. The disciplined breathing. The subtle shifts in stance that only a true master possessed.
This was no illusion.
No trick of light.
No dream clawing its way into the waking world.
The figure before him was real.
And it was him.
Yoriichi.
Unchanged. Untouched by time. Not aged or worn, not broken by death's embrace. As though the centuries that had passed since their last battle had never existed at all. As though fate had rewound itself to place them once more in each other's path.
Kokushibo's breath caught—if only for a fraction of a second.
The man he had killed. The man he had envied. The man he had feared.
The man he could never surpass.
Standing there, once again, in the prime of his strength. A presence so absolute it seemed to silence the world around it
How…?
How can it be possible?
His mind searched for reason, but nothing came—only the sound of his own breath echoing beneath the weight of that impossible truth.
I killed him… I was there… I ended it with my own hands… centuries ago.
The blood. The silence after the strike. The stillness that followed. He remembered it all.
Yoriichi had fallen. The man whose shadow had haunted his life had finally disappeared—until now.
And yet, here he was.
Alive. Whole. Unscarred by time or death.
Standing tall with the same unwavering presence… the same eyes that had once looked through him—not at him—as if he was already defeated.
Kokushibo's jaw tightened.
This defies all logic. Even Muzan would doubt this.
It wasn't a trick. It wasn't a clone. Not a puppet or a memory reborn. The Transparent World didn't lie.
It was him.
And for the first time in centuries, Kokushibo felt it again—not rage. Not envy.
But dread.
This… this is what Muzan felt.
Kokushibo's six eyes locked onto the figure standing just a few paces ahead. The same brother. The same threat. The same light that had always outshined him—now returned from a grave he was never meant to leave.
I didn't believe then… but now…
He clenched his jaw, the sensation clawing at something buried—deep beneath demonhood, beneath blood and evolution—beneath everything he had become.
In the fleeting moments following Enmu's death, a shadow of conversation resurfaced—an earlier exchange with Muzan, flickering like a dying ember in Kokushibo's mind.
The Infinity Castle whispered with its own madness.
Walls shifted with no logic, ceilings turned to floors without falling, and distant drums echoed like the heartbeat of a dead god. It was a realm not made for mortals—where time bent, where direction meant nothing, and where two beings who had long since left the boundary of humanity stood facing something darker than silence.
Kokushibo stood at the center of the floating platform, arms relaxed at his sides, his long black hair brushing against the curve of his armored haori. His six eyes were open but still—watching without blinking. Patient. Timeless.
Across from him, at the edge of the abyss, Muzan Kibutsuji stared into the shifting void, his expression unreadable. He didn't glance back. He didn't need to. The castle obeyed his will, and its very pulse slowed as his voice broke the silence.
Muzan spoke plainly. No ceremony. No emotion.
"One wearing hanafuda earrings. A familiar haori. The same kind of presence."
He didn't finish the name. He didn't need to.
A faint vibration passed through the castle floor, like a breath caught in the lungs of the infinite. Kokushibo did not move, but his eyes narrowed slightly, his jaw shifting with the weight of something old—older than memory, heavier than regret.
"A false descendant?" asked by Kokushibo itself.
"No," Muzan replied. "Not entirely. It wasn't a coincidence. Not a mimic. His appearance… shattered Enmu's mind."
Now, he turned—just slightly. Enough that Kokushibo could see the gleam of crimson in his eyes.
"My cells inside Enmu recoiled," Muzan said coldly. "The boy didn't just look like him. He made my own influence—my very blood—hesitate. Even with centuries between us, it was as if the scent of that man still lingered. As if the sun had never truly set on him."
A silence followed—one that didn't belong to the Infinity Castle, but to something deeper. Something only the two of them could stand inside.
Kokushibo's voice was quiet when it came. Flat, but edged.
"I killed him."
His words rang out like a decree. Final. Unflinching.
"I watched his life burn out. I saw the last breath leave his lungs. I severed him."
"Then someone walks this world carrying what shouldn't exist," Muzan murmured. "And it is interfering with my plans."
Kokushibo's hand drifted—just slightly—toward the sheath of his blade. Not to draw it. Not yet. But the gesture was enough to warp the floor beneath him, like the world itself leaned away from the thought of his sword being unsheathed.
"No one has the right to wear his face," Kokushibo said. "Not without consequences."
Muzan gave no orders. He didn't need to.
Kokushibo was already moving.
"If it's an illusion, I'll tear it apart," he said. "If it's a fool borrowing his shape, I'll grind him into the soil."
But now—standing amidst the broken earth, surrounded by the dying echoes of battle—Kokushibo knew.
This was no pretender.
No fool wearing the mask.
It was him.
Yoriichi Tsugikuni.
The blood, the rhythm, the scent of his sword—it all told the same story, one that could not be forged or faked. Kokushibo had seen the truth through the Transparent World. He had watched the perfect flow of muscle, the stillness of breath, the harmony that existed in only one man.
There could be no mistake.
Centuries ago, he had believed Yoriichi to be dead—reduced to dust beneath the final clash of their blades. But now, as the fading embers of Enmu's corpse danced around his feet, Kokushibo felt it deep in his bones.
He had returned.
And he was not diminished.