The western outpost had long been reduced to rubble by the two warriors' battle. The moonlight of the deep night was almost smothered by rising smoke and dust, spilling through the broken rooftop in scattered, trembling patches across the shattered ground.
The sharp clang of metal and the muffled thrum of clashing auras filled the air, making even the atmosphere tremble.
Uzui Tengen's twin Nichirin blades gleamed with silver-violet light, locked against Akaza's fists. Power rippled around them, raw and violent, lifting shards of stone into the air under invisible pressure.
A metallic screech tore through the chaos. Akaza's fist suddenly tightened, black fighting energy surging up the blade. Tengen felt a burning pain shoot through his hands—the impact nearly tore his weapons free.
Gritting his teeth, he twisted backward, using the recoil to flip away and land lightly on a broken beam. Blood seeped from a bruise under his left ribs—an injury from a miscalculated rhythm earlier, when Akaza's fist had grazed him. Every breath now pulled at the wound in sharp pain.
Then, silently, a dark figure landed atop a nearby crumbling wall.
Tomioka Giyu gripped his Nichirin sword, dark blue pupils scanning the battlefield. His gaze lingered briefly on Tengen's bleeding side, then on Akaza's aura-wreathed fists, before he settled into the shadows without stepping forward.
Akaza's sharp eyes had already caught sight of him. A flicker of irritation crossed his golden pupils—but there was far more excitement than anger.
"Hey, Mushiki! Don't interfere!" he roared, voice thick with battlelust. "This is my fight! A duel between true warriors!"
Even as he spoke, his fists didn't relax. Black fighting energy gathered at his fingertips, ready to explode again at any moment.
Giyu inclined his head slightly, a faint sense of relief washing through him.
Good. I never wanted to help him kill a Hashira anyway.
He stepped back, leaning against the wall's shadow, giving the field entirely to the two combatants. He watched quietly, studying Akaza's movements—the flow of his fighting aura, his rhythm, his strikes.
Akaza's mastery of battle energy far surpassed his own.
If I could learn to control energy as freely as he does… maybe I could reach the "Supreme Realm" more easily, Giyu thought silently.
Tengen, panting hard, wiped blood from the corner of his mouth. His twin blades spun rapidly between his fingers, producing a high-pitched hum, sharp and rhythmic like a swarm of bees.
"Upper Moon Three, huh? You've got some skill," he said with a grin. "But I've finished my score—your every punch, every motion, even the rhythm of your aura, is written in it! Now, prepare to face my flashy victory, monster!"
The "score" he spoke of was the essence of Sound Breathing—a technique that recorded an opponent's attack rhythm, turning it into a visible musical pattern. By reading that pattern, a skilled fighter could predict movements and strike in the perfect gap.
The hits Tengen had taken earlier weren't mistakes—they were part of his process to complete the score. Now, with the rhythm set, the Sound Hashira could finally unleash his true strength.
"Score?"
Akaza's eyes lit up with excitement. A feral smile twisted his lips as black energy surged around him, his muscles tightening with explosive force.
"Never heard of that before, Tengen. Let's see how strong your little 'score' really is!"
In a flash, he stomped the ground—stone cracked beneath his feet—and his body shot forward like an arrow loosed from a bow. His right fist blazed with condensed black energy as he roared:
"Destructive Death: Compass Needle!"
The punch ripped through the air, the sheer pressure scattering debris in all directions, moving so fast it left a blur of afterimages.
But Tengen had already foreseen it. Crossing his twin blades, he deflected the strike while sliding to the side, using the momentum to counter.
"Sound Breathing, Fourth Form: Constant Resounding Slashes!"
Silver-violet blades flashed like a storm of rain, each strike threading perfectly between Akaza's fists—the calculated weak points in his rhythm.
Akaza's pupils narrowed. He hadn't expected Tengen to evade so precisely, much less strike back with such accuracy.
He raised his arms to block, the air erupting with a rapid series of metallic clashes.
Clang, clang, clang!
Sparks scattered wildly. The collision of sound waves and fighting energy created invisible shockwaves that shattered broken beams around them into splinters.
"Good! That's more like it!" Akaza laughed, voice vibrating with thrill.
His left arm shifted suddenly, dodging Tengen's guard as his fist spiraled forward.
"Destructive Death: Air Type!"
Black energy spun violently around his knuckles, forming a vortex so dense it distorted the air. A direct hit would twist flesh and bone to pulp.
Tengen's expression hardened. His twin blades snapped together, the vibration frequency climbing in pitch until the edges glowed faint red.
"Sound Breathing, Fifth Form: String Performance!"
A burst of sound exploded outward—the pressure warped the air, forcing Akaza's rotating punch to lose its rhythm.
Tengen leaped backward, widening the distance while separating his blades once more. Each point aimed at Akaza's shoulders, steady and confident.
"Your fists are fast, but once they're disrupted by my sound waves, your rhythm falls apart. Every motion you make is part of my score now!"
Akaza grinned, baring his fangs.
"Is that so? Then let's see how well your score keeps up with this!"
With a deafening roar, he slammed his foot into the earth—cracks spiderwebbed outward as black energy erupted beneath him.
Around Akaza, black fighting energy suddenly condensed into dozens of phantom fists, surging toward Tengen in a violent storm.
It was his Blood Demon Art—by throwing punches so fast they created afterimages, he confused his opponent's vision before striking with a hidden, real attack.
"Destructive Death: Disorder!"
The barrage of fist shadows filled every inch of space, sealing off all of Tengen's escape routes.
But Tengen didn't panic. His twin blades moved in perfect rhythm, every swing aligned with the beat of his Sound Breathing and his inner score.
"Sound Breathing, Third Form: Echo Break!"
As his blades cut through the air, faint violet traces of sound rippled outward. Each one hit its target with precision, slamming into the phantom fists.
A series of muffled explosions rang out—bang, bang, bang!—as every fist shadow shattered into black energy that scattered and faded in the air.
But the instant the last one vanished, a chill raced down Tengen's spine.
Danger—behind him!
Akaza's real attack had circled around unnoticed.
"I've won!" Akaza's voice burst right beside his ear as his right fist, radiating with destructive energy, drove straight toward Tengen's back.
"Destructive Death: Annihilation Type!"
Tengen's pupils shrank sharply. Acting purely on instinct, he twisted his body sideways—
A harsh tearing sound followed.
The blow grazed his back, shredding his uniform to pieces. Blood splattered across the floor, staining the edge of his haori deep red.
Using the force of the impact, Tengen spun on his heel and countered, blades flashing in a crosscut toward Akaza's throat.
"Sound Breathing, Second Form: Clawing Resonance!"
Akaza hadn't expected Tengen to fight back after taking such a hit. He leaned back in haste, barely dodging—but not fast enough. Both his arms were sliced clean off in a burst of blood and smoke.
He stumbled two steps back, but his golden eyes burned hotter than ever. "Good! That's it! Amazing, Tengen! Become a demon!
With swordsmanship and fighting instincts like yours, if you turned, you'd reach the Supreme Realm in no time!"
Tengen exhaled heavily, sweat and blood dripping down his chin. He didn't bother replying—he simply flipped his blade downward, thumbing the handle toward the ground in defiance.
Akaza's grin froze. His expression hardened as he inhaled deeply. The black aura around him condensed, thick and solid like armor. His muscles swelled; his bones cracked and shifted under the pressure.
It was his ultimate enhancement—pushing his Blood Demon Art to its absolute limit, doubling his strength and speed.
"Destructive Death: Final Form—Hell Gate!"
Akaza vanished from sight. In the blink of an eye, he reappeared in front of Tengen, both fists striking at once. The black aura merged into the shape of a massive gate, slamming forward with crushing force.
The power and speed were overwhelming—far beyond anything before. The air itself screamed from the pressure.
Tengen's face tightened. He knew this was Akaza's killing blow. He couldn't dodge—it was too fast. The only choice was to meet it head-on.
He crossed his twin blades above his head, channeling every ounce of strength into his arms. Sound Breathing surged to its peak, the silver-violet glow of his blades blending with a burning crimson aura.
"Sound Breathing, Sixth Form: Fiery Arrow Burst!"
This was the strongest technique of Sound Breathing—raising vibration frequency to the absolute limit until the blade produced searing heat, fusing the push of sound waves with explosive destructive power.
The moment the fiery light met the black aura gate, the entire ruin shook violently. A roaring blast tore through the night sky, hurling debris in every direction.
Even Giyu, watching from afar, felt the shockwave hammer against him and had to raise an arm to block flying rubble.
In midair, the clash raged on. Silver-violet light and black energy collided again and again, emitting a shrill, piercing wail that split the silence.
Tengen's arms bulged with veins, the wound on his back tearing open further. Blood streamed down his arms and onto the twin blades, but still he didn't loosen his grip.
Across from him, Akaza's expression twisted with strain, the energy around his fists flickering as it was slowly consumed by Tengen's burning light.
"Not yet!"
Akaza roared, forcing his aura to surge once more. The black gate expanded, pressing the fiery light backward by half an inch.
Tengen grit his teeth, growling through the pain, the light on his blades burning brighter.
"I won't lose! The will of the Demon Slayer Corps will never fall to a monster like you!"
Neither side yielded. The power struggle dragged on, each wave of energy clashing and fracturing, heat and shadow entwined in a violent dance.
From the distance, Giyu's dark blue pupils flickered with conflicting emotion.
He wanted Tengen to win—but he couldn't let Akaza lose too badly. If Akaza were defeated outright, Muzan's suspicion would fall immediately.
He tightened his grip on his Nichirin sword, ready to intervene the moment one side faltered.
In the center of the battlefield, the two forces tore through the night—flames of sound clashing with darkness made solid.
At last, sparks burst outward as Tengen's left blade sliced through Akaza's regenerating arm, severing it once again.
But Akaza, unfazed, shifted his stance, channeling energy into his legs.
"Destructive Death: Leg Type—Flying Planet Thousand Wheels!"
His kicks came faster than sight, each one laced with spiraling energy.
Tengen raised his blades to block, but the relentless assault struck like a storm. The impact sent him flying, blood spraying from his lips as he crashed into the wreckage below.