Tanjiro's throat tightened. The words "Giyu-san, why are you doing this?" stuck to his tongue, but the icy emptiness in Mushiki's eyes crushed them before they could leave his lips.
This wasn't the Giyu he knew. The Giyu he remembered—though expressionless—had always carried a scent of quiet gentleness. But the man before him, with pupils as cold as winter steel, looked at them as if they were nothing more than debris blocking his path.
Mushiki leapt lightly down from the rooftop. The hem of his black haori brushed against the ashes on the ground without stirring even a speck of dust.
In his right hand, he gripped his Nichirin Sword. Faint blue moonlight rippled along its surface as his gaze settled on Tanjiro. For an instant, his brow furrowed ever so slightly—there was something strange about the boy's scent. His body reacted in two ways at once: half of him screamed to kill this human, the other half trembled, as though some buried memory was trying to surface.
"This feeling… is strange."
He murmured quietly, fingers tightening around the hilt.
Then Muzan's voice slithered into his mind like a serpent.
Mushiki, don't hesitate. Kill him.
The flicker of hesitation in him shattered instantly.
Mushiki ignored the foreign heat burning in his veins. His foot brushed the ground and his body vanished in a blur. The blade in his hand rose in a familiar motion—Water Breathing, First Form: Water Surface Slash—but sharper, fiercer, his version no longer gliding low, but cutting upward with explosive force, as if tearing the sea apart.
"Look out!"
The Flame Hashira, Rengoku Kyojuro, roared. In an instant, he appeared beside Tanjiro, his large hand pressing down on the boy's neck, forcing him flat against the ground.
A heartbeat later, a crescent of pale blue water surged from Mushiki's blade, sweeping horizontally through the space where they had stood.
With a crash, the stone wall behind them split cleanly in half, the surface smooth as glass. Rubble trickled down, revealing the dark alley beyond.
Tanjiro lay flat, his heart hammering wildly, sweat soaking through his uniform. One strike—just one second slower—and he would have been decapitated.
Mushiki lowered his blade, turning toward Rengoku.
The faintest ripple flickered in his ice-blue eyes. "Your reflexes are quick."
He could feel it clearly—the fierce, blazing resolve radiating from the man before him. It was heat itself: relentless, unwavering.
Rengoku rose, positioning himself protectively in front of Tanjiro. Flames coiled around his Nichirin Sword, burning bright orange-red. His voice was heavy. "Tomioka… what happened to you? You're not someone who would raise your sword against your comrades!"
He locked eyes with Mushiki, searching desperately for the shadow of the man he once knew—but found only a dead, frozen void.
"Giyu?"
Mushiki frowned slightly, confusion flickering across his face. "My name is Mushiki. Not this… Giyu you speak of."
He paused, tightening his grip on the sword. "Who are you?"
"Rengoku Kyojuro, Flame Hashira of the Demon Slayer Corps."
Rengoku's tone carried a quiet sorrow. "So you've become a demon… and lost your memories too."
"Flame Hashira… Rengoku Kyojuro."
Mushiki repeated the name softly, as if testing the sound. Then, his lips curved into a faint, cold smile. "Understood. A Hashira, then. That means I can take this fight seriously. Come—show me your flames."
Before his voice faded, Mushiki moved.
He didn't use Moon Breathing this time. Instead, his breathing shifted—purple fire erupted along his blade. It was Flame Breathing, but not like Rengoku's. His flames glowed violet, cold and eerie, their chill strong enough to freeze the air itself.
"Flame Breathing, First Form: Unknowing Fire!"
The violet blade streaked forward like a meteor, twice as fast as Rengoku's own.
Rengoku's pupils contracted sharply. He raised his sword just in time.
"Flame Breathing, First Form: Unknowing Fire!"
Orange-red collided with violet, releasing a screeching hiss as heat and cold clashed, twisting the air into a violent shockwave.
A surge of force shot up Rengoku's arms—his grip trembled, his palms numbed. He slid back three steps before regaining his balance.
"Using only the basic form?"
Mushiki's expression was calm, almost bored. "You're a Hashira, aren't you? Don't tell me you're holding back. Show me something real."
He shifted his stance again, his blade now wrapped in flowing blue ripples.
"Water Breathing, Third Form: Flowing Dance!"
The sword moved like water—fluid and unpredictable—alternating between swift, sharp arcs and soft, deceptive feints that forced Rengoku on the defensive.
Rengoku gritted his teeth, raising his own flames to their peak.
"Flame Breathing, Fourth Form: Blooming Flame Undulation!"
A surge of heat burst from his blade, creating a wall of living fire that blocked the incoming water strikes.
But Mushiki's movements were too fluid. His Flowing Dance shifted mid-strike, slipping between the waves of flame, his sword darting straight for Rengoku's waist.
Rengoku twisted just in time—the blade grazed his uniform, leaving a charred streak across the fabric.
The water pattern had carried traces of flame—it burned on contact.
"I can't keep playing defense!"
Rengoku inhaled deeply, his flames thickening, burning brighter and hotter until they coiled around his sword like molten sunlight.
"Flame Breathing, Eleventh Form: Burning Sun!"
His own creation—a killing strike. The heat surged, and even the air trembled with the roar of the fire. His blade swung down, wreathed in a dragon of flame that rose toward the sky before diving at Mushiki.
Mushiki's eyes sharpened. For the first time, he looked intrigued. "That's impressive."
He rotated his wrist slightly, and the water markings on his blade condensed into a spiraling vortex.
"Water Breathing, Eleventh Form: Dead Calm."
A massive swirl of tranquil blue water collided with the fiery dragon.
The impact roared like thunder. Orange-red flames and pale-blue waves consumed each other, twisting violently before fading into nothing.
Rengoku's Burning Sun—completely neutralized.
"How… how is that possible…?"
Rengoku's pupils shrank, but before he could react, Mushiki was already in front of him. The pale blue glow of Moon Breathing rippled along his Nichirin Sword.
"Moon Breathing, Third Form: Loathsome Moon, Chains!"
The curved slash tore through the air like a crescent moon. Rengoku barely managed to raise his blade in time—
Clang!
The impact rang out sharp and clear. His Nichirin Sword was torn from his grasp, spinning into the air. His body shot backward like a broken kite, slamming hard into the wall. Blood sprayed from his lips as he slid down, leaving a red trail along the stone.
"Rengoku-san!"
Tanjiro's voice cracked as he ran toward him, but Mushiki's cold glare froze him in place. The killing intent in those dark blue eyes was so heavy it felt tangible—like a blade pressing against his throat.
Even so, Tanjiro gritted his teeth and forced himself forward. He couldn't—he wouldn't—let Rengoku fall.
Mushiki swung casually. A thin arc of pale-blue water shot out from his blade, slamming into Tanjiro's chest with a heavy thud.
"Ugh—!"
Tanjiro was thrown back, crashing into a heap of broken bricks. Blood poured from his mouth, his Nichirin Sword clattering to the ground beside him.
Mushiki stepped toward Rengoku, standing over him. His voice was calm, almost detached. "Your strength is remarkable. If you became a demon, you could grow even stronger—perhaps even reach a higher realm. Do you wish to become one?"
Rengoku coughed violently, blood staining his teeth, but his eyes never wavered.
A faint, fearless smile curved his lips. "I am Rengoku Kyojuro, the Flame Hashira. My life's purpose is to protect humanity and slay demons. To turn me into one… is impossible!"
"What a pity."
Mushiki gave a slight shake of his head. Without another word, he drove his sword straight into Rengoku's heart.
"Rengoku-san—!"
Tanjiro's eyes widened in horror. He screamed until his throat tore, dragging his battered body from the rubble. Every inch of him bled, but his eyes burned with fury and grief.
Mushiki pulled the blade free and wiped away the blood. Turning slowly, he began walking toward Tanjiro. His blue slit pupils glowed faintly—cold, unfeeling. This boy was a distraction. He needed to be erased.
Just as the blade rose for the killing strike, a flash of blue-green light slashed across the air, intercepting the attack with a ringing clang!
The sparks illuminated the face of the newcomer—Tō.
His cheeks were streaked with tears, his eyes red, his hands trembling as he gripped his Nichirin Sword so tightly his knuckles turned white. His voice broke as he shouted, "Sensei… how could you do this? Rengoku-san was our comrade! Did you forget? The days you taught me Water Breathing? The words you said—to protect everyone? Have you forgotten all of it?!"
Mushiki's brow furrowed. A sharp, searing pain stabbed through his skull, as if something inside him was trying to break free.
"Giyu… Water Breathing… comrades…"
The words echoed in his head like needles. He stumbled slightly, clutching his temples as pain wracked his body.
With a sudden roar, he swung his sword, knocking Tō's blade aside and kicking him squarely in the chest. Tō's body flew backward, crashing into the ground.
"Don't call me that name!"
"My name is Mushiki!"
He shouted in fury, one hand still pressed against his temple. The pain was unbearable—each memory, each word ripped at his mind. The sight of Tō's tear-streaked face only made his heart twist harder.
Tanjiro, seeing his chance, forced himself upright. He staggered to his fallen sword and gripped it tight.
Then—his forehead burned. The pain was sharp and deep, as if something inside was breaking through his skin.
He reached up, fingers brushing against the rough outline of a mark—a new, glowing red flame pattern spreading across his brow.
The Demon Slayer Mark.
Tanjiro froze in shock. Then, suddenly, power surged through every vein in his body. His heartbeat thundered. The cracked Nichirin Sword in his hand pulsed faintly with a red glow.
Mushiki steadied himself just in time to see Tanjiro rush forward.
This time, the boy's speed was far beyond before—blindingly fast.
A trail of red flames streaked behind his blade.
"Hinokami Kagura: Fake Rainbow!"
A blur of fire and motion—the sword's path twisting like a phantom rainbow, impossible to predict.
Mushiki's eyes widened. He raised his blade to block—but he was a heartbeat too late.
Slash!
Tanjiro's sword cut deep across his back. Flesh tore, bone cracked.
He staggered, stunned. The wound burned, refusing to heal. A sharp, searing pain spread outward.
The red glow—its heat was eating away at his regeneration.
"Impossible…"
Mushiki turned, disbelief written across his face. The wound still smoked, the flesh refusing to knit. The red Nichirin Blade… it could halt a demon's healing.
Tanjiro panted, his grip trembling, yet his gaze was fierce. He could feel it—the mark heightening every breath, every heartbeat. His movements flowed perfectly with his breathing, his sword sharper, faster, alive.
Mushiki's eyes hardened.
Enough hesitation.
He spread his left hand, summoning a surge of blue water that twisted around him. The air thickened, growing heavy and damp.
"Blood Demon Art—Essence of Water: Water Vortex Domain!"
A massive whirlpool erupted around him, spiraling outward. Everything caught within it—stones, debris, even the air—was torn to dust. Light itself bent and shimmered in the distortion.
A suffocating sense of despair blanketed the battlefield.
Tanjiro and the barely-standing Tō exchanged a glance. Their faces were pale, but their eyes were unshaken.
They tightened their grips on their Nichirin Swords and stood side by side, facing the heart of the swirling blue storm.
The red flame and blue water met at the center, clashing, roaring.
The final stage of their life-and-death battle had only just begun.