#A/N: "I'm not sure if this is good enough, I wrote it, reread it, then rewrote it a bunch of times, so it might look a bit messy? And the Fifth Form of Smoke Breathing appears here!"
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In the middle of the forest surrounding the Ubuyashiki Estate, an open field lay bathed in morning light.
Amidst the dense forest, even as morning faded into afternoon, dew still clung to the blades of grass, glistening softly. The distant song of cicadas mingled with the gentle rustle of wind weaving through the cedar branches.
There, two figures stood facing one another.
Kagerou, still young, slight of frame, with gray eyes as calm as smoke itself, held an ordinary tanto in one hand, and his kiseru in the other. The thin trail of smoke curling from its tip wove lazily into the air, coiling and fading like his breath.
To his side, several Kakushi watched silently, medical supplies ready in case the "demonstration" turned into something else.
Behind them stood Kagaya Ubuyashiki, serene as ever, his eyes following every movement; Gyomei Himejima, his hands pressed together in prayer; and Shinjuro Rengoku, arms crossed, unreadable, though his gaze betrayed a father's quiet concern.
Across the clearing, Tengen Uzui stood, his twin blades gleaming faintly in the sun. He rested them on his shoulder, his trademark grin sharp and amused. The Sound Hashira exuded confidence, colorful, flamboyant, and just a little mocking.
"…What are you planning to do with that toy, boy?" Tengen drawled, tilting his head. "Smack me with it?"
Kagerou didn't answer right away. He raised the kiseru to his lips, took a slow puff, and exhaled. A stream of smoke drifted forward, curling around him.
"Yeah," he said softly. "Something like that"
Tengen chuckled, eyes glinting. "Talk about attitude. Is this how your father taught you to speak to a Hashira?"
Kagerou's lips curved faintly, not quite a smile. "Hmm~ more or less"
"Yo-" Tengen began, but his voice trailed off. His expression shifted subtly as he noticed it, the haze thickening around them.
The air had changed.
"…This…?" he muttered, glancing around.
The once-clear clearing was now shrouded in a thin mist. It wasn't natural fog; it clung too closely, moved too deliberately. His trained ears picked up the faintest sound, the subtle hiss of air currents breaking rhythm.
"Ohh~ you only noticed it now?" Kagerou's voice came, calm and detached, from somewhere within the veil. "I was hoping to buy more time… but I think this is enough... First form: Kon'en(Soul Mist)"
The smoke curled and twisted around Tengen, swallowing the morning light. His sharp hearing strained, yet every echo, every rustle, every breath sounded wrong, layered, overlapping.
It was like the forest itself had begun to breathe.
Tengen's eyes narrowed. The air around them thickened, the mist curling and writhing like a living thing. It wasn't fog anymore, it moved with intent, coiling and stretching as though it possessed a will of its own.
His Sound Breathing senses twitched. The world of rhythm, normally so clear to him, the pattern of breaths, heartbeats, shifting feet... was gone.
The boy's breathing had vanished, swallowed whole by the haze.
"…Oh?" Tengen muttered, pulling his chained blades free with a sharp metallic clang. "Now this is getting interesting"
The chain between his swords jingled as he spun them in a wide, lazy arc, flamboyant, precise, and deliberate. "Let's see how long you can hide, kid"
"Hide?" Kagerou's voice drifted through the mist, calm and distant, yet somehow right beside him. "Smoke doesn't hide. It obscures"
Tengen's grin widened. His eyes darted through the fog, his ears searching for even the faintest clue, but each time he tried to catch the boy's heartbeat, it slipped away. His rhythm, his sound, his presence... Gone.
A whisper brushed past his ear, soft as breath. "Smoke Breathing: Third Form - Fukuei (Shrouded Shadow)"
Tengen's sharp eyes widened. The fog thickened violently, forming silhouettes, dozens of Kagerous, darting between the trees, each one moving differently, each one real enough to cast a shadow.
"Ha! Illusions?" Tengen roared, spinning both blades in a deadly spiral. "You think I can't handle noise? My hearing-"
But his own rhythm betrayed him.
Every time he locked onto a heartbeat, it changed. Every movement in the mist sounded real, each heartbeat, each breath perfectly replicated by the shifting smoke.
For the first time, Sound Breathing failed to find the truth.
"Damn…!" Tengen gritted his teeth, blocking a blow from his left, only for another to come from behind. His blades met air again, smoke slicing across his cheek like the kiss of a phantom blade.
Kagerou's real voice whispered close to his ear: "Don't rely too much on your senses, Hashira"
Then he vanished again into the swirling gray.
From the sidelines, Gyomei's blind gaze lifted slightly. "…His presence disappears completely," he murmured. "Even I can't sense him properly"
Kagaya's soft smile deepened. "That's the nature of smoke, fleeting, shapeless, unpredictable. Yet it always returns, doesn't it?"
Shinjuro said nothing, but the small twitch at the corner of his lips spoke volumes, pride, restrained but burning bright.
Back on the field, Tengen landed, breathing harder now, eyes sharp.
"You've got skill, kid. But if you want to impress me..." Tengen said, raising both blades, muscles coiling. "... Then show me something worth watching!"
Kagerou didn't answer. Instead, he took one slow breath, exhaled through his lips, and the entire clearing seemed to darken.
"Fourth Form - Genbu (Phantom Dance)"
The smoke exploded outward in a storm of gray and silver. Dozens of figures stepped out from it, each one Kagerou, each one holding a blade.
Tengen's grin faltered for just a heartbeat. "…Oh, hell"
They moved together, flowing like water, every phantom's strike synchronized perfectly, every slash merging into the next. The forest erupted in a symphony of ringing steel, each illusion moving with the grace of a spirit and the precision of a swordsman.
Tengen blocked one blow, two, then three, but each parry left him open for the next. He felt the pressure multiply, the rhythm of the boy's breathing threading through every illusion.
Smoke wasn't supposed to press like this. Yet every phantom carried real weight, every movement tied to Kagerou's heartbeat.
"You leave me no choice, Kagerou…" Tengen's voice was steady, no longer calling him boy, but his name, a mark of respect for the swordsman standing before him.
He spun his dual blades, exhaling deeply as his stance lowered, muscles coiling, breathing shifting into perfect rhythm.
"Sound Breathing, Fourth Form: Kyōzan Muken (Constant Resounding Slashes)!"
The mist exploded outward as his blades cut in perfect circular arcs, the chained swords singing through the air with deafening force. Every movement sent pressure waves that dispersed the smoke. But each time he cleared a space, the smoke returned, thicker than before, as if the air itself defied him.
From within the haze came Kagerou's calm murmur: "Smoke Breathing - Fifth Form: Kien no Kagerō (Vanishing Ember)"
Tengen's eyes widened, and for just an instant, the boy disappeared completely. No sound. No scent. Not even the faintest ripple of breathing.
Then-
*Clang!*
The boy appeared right in front of him, his Tanto only inches from his throat, and stopped only because Tengen caught the blade with his chain in the last second.
A moment of silence.
Then Tengen laughed, loud, bright, genuine as Kagerou vanished once more into the mist. "Hah! You've got guts, kid! And skill! I like that!"
A whisper drifted from within the swirling haze. "Is it flashy enough for you?"
Tengen's grin widened, sweat tracing down his temple. "Now that's what I call a performance!"
He stomped forward, twin blades crossing, air vibrating around him. "Sound Breathing - First Form: Todoroki (Roar)!"
With a roar, the Sound Hashira slammed both swords into the ground, unleashing a concussive blast that shredded the surrounding mist.
When the smoke cleared, Kagerou stood several meters away, one knee bent, Tanto pointed down, his breathing calm but heavy.
Tengen lowered his blades, grinning wide. "You've got style, kid. Reckless, but real style"
Kagerou smiled faintly. "Thanks. But I wasn't trying to impress you"
"Oh? Then who?"
Kagerou's gray eyes flicked toward Kagaya and Shinjuro. "Just proving that my father didn't lie"
For a moment, silence fell. Even Tengen had no witty retort.
Then Kagaya's gentle applause broke it, soft and warm.
"Well done, Kagerou-kun," he said. "Your Smoke Breathing… truly lives up to its name, but that's enough. You've both shown us something remarkable today"
He looked at Kagerou. "A heart that does not waver, even in the haze, and a spirit that continues to burn. Shinjuro, you've raised a fine child"
Shinjuro only smiled faintly, muttering, "…He raised himself more than I did"
As the mist cleared fully, the morning light streamed through the trees again, golden rays piercing the last traces of smoke drifting across the field.
And for a moment, Tengen couldn't help but grin again, "You know, Kagerou… 'Smoke Hashira' has a nice ring to it"
Kagerou exhaled softly, smoke curling from his lips. "Let's see if I live long enough to earn that title first"
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- Fifth Form: Vanishing Ember (Go no kata: Kien no Kagerō)
#Description:
The user exhales a thin stream of smoke, then vanishes completely into it.
Their presence fades from sight, sound, and scent, and even the rhythm of their breathing disappears.
To onlookers, it's as though the user has evaporated from existence, leaving behind only a faint shimmer where the smoke once was.
#Effect:
Grants complete sensory erasure for a short duration, no sound, smell, or motion detectable even by demons with enhanced perception.
Allows the user to move freely and reposition undetected, making it ideal for assassinations or evasion.
The technique manipulates airflow and body rhythm to synchronize with ambient smoke, blending perfectly with the environment.
#Limitation:
Cannot attack while the form is active, any offensive movement breaks the concealment immediately.
Extremely taxing on the lungs and concentration; prolonged use may cause internal bleeding or loss of consciousness.
Requires a smoke source or lingering mist to activate effectively.
In clear, windless air, it loses potency.
The user must fully hold their breath; any exhale or sound disrupts the invisibility.