Demon Slayer Corps Headquarters — training grounds.
Chika and Rengoku Kyojuro stood on opposite sides of the arena, eyes locked on each other.
Their Nichirin Blades gleamed in the morning air — one a deep, serene blue, the other a blazing crimson red.
Rengoku's lips curved into a proud smile. "A fine blade you have there!"
Nichirin Blades were originally colorless. Only after a swordsman mastered their Breathing Style would the blade reveal its hue. And even among those colors, there was distinction — a reflection of the wielder's spirit.
In Rengoku's eyes, the clear blue radiance of Chika's sword was proof of her strength.
Chika steadied her breathing in rhythmic focus, eyes narrowing. She wanted to begin with Water Breathing, to test how many of Rengoku's blows she could withstand in that form.
At the edge of the training field, Mitsuri Kanroji stood ready to referee.
She looked between them, took a deep breath until her cheeks puffed out, and raised her arm high.
"Begin!"
The moment her voice echoed, both swordsmen moved.
BOOM!
The first clash of steel reverberated across the entire training ground — the metallic roar was so sharp that even those in the distant dorms lifted their heads.
No techniques, no fancy forms — just raw strength.
From Chika's side, droplets of water scattered like shards of glass.
From Rengoku's, sparks of fire exploded into the air.
Blades collided.
Breath collided.
Their fighting spirits collided.
Rengoku's wrist trembled slightly, surprised by her strength.
From the sidelines, Mitsuri cupped her hands and shouted, "Be careful, Rengoku-sensei! Chika's strength isn't any weaker than mine!"
Rengoku grinned faintly, acknowledging the warning. He could feel it — the raw pressure behind each swing.
Steel rang again and again.
Each time their blades met, sparks and droplets flew.
Despite Flame Breathing's offensive nature, Rengoku found himself momentarily on the defensive, blocking each of Chika's fierce strikes.
But that wasn't because she was overpowering him — no, it was proof of his mastery.
Even when not fighting within his strongest rhythm, Rengoku's swordsmanship was impeccable, capable of parrying her every blow with calm precision.
So this is the Flame Hashira…
He really was powerful.
But Chika had expected nothing less.
Water Breathing — the balanced style of the five basic forms.
It could be called "versatile" by those who admired it… or "mediocre" by those who did not.
Thunder Breathing: fastest.
Wind Breathing: most cutting.
Flame Breathing: most forceful.
Stone Breathing: most overwhelming.
Though Urokodaki believed Chika's talent in Water Breathing surpassed even Giyu Tomioka's, she had yet to reach the level of creating a personal form like Giyu's Eleventh Form — Dead Calm.
Chika unleashed technique after technique, her sword flowing like a surging current — but each strike was met and deflected with fiery grace.
Finally, she leapt back, exhaling heavily. Across from her, Rengoku rolled his shoulders, flexing his wrist where he'd absorbed the shock of her attacks.
"Chika," he said warmly, "your strength is truly impressive. Your swordsmanship isn't just brute force — it's refined. In the art of Water Breathing, I can't teach you much more. But Giyu can. Don't let his stoic face fool you — if you ask, he'll teach you sincerely. You have great potential."
Chika smiled, catching her breath — but she wasn't done yet.
Rengoku's eyes narrowed slightly as he noticed something strange.
Her steady Total Concentration Breathing: Constant… suddenly stopped.
Was she exhausted already? After only a few exchanges?
That didn't seem right.
Before he could voice his thought, her blue blade began to fade — its color draining away until it was pure, gleaming silver.
Rengoku blinked in confusion. A blade losing color?
But the next second, both he and Mitsuri gasped.
From the hilt outward, a dark sheen began to spread — black seeping into the metal until it consumed the entire blade.
"The Black Blade…?!" Mitsuri exclaimed, her hands covering her mouth.
She had never heard of such a phenomenon — a Nichirin Blade changing color twice.
Chika's hand tightened on the hilt. Her breathing shifted, slower, deeper… different.
Dark flame ignited along the length of the sword — not the warm glow of Rengoku's fire, but something primal and ancient.
Rengoku's face twisted through shock, confusion, awe… and finally, joy.
Yes — joy.
This was no mere opponent.
This was a warrior.
Gripping his sword in both hands, Rengoku grinned broadly, his pupils shining with the reflection of her strange black flame.
He didn't ask what style she used — he didn't need to.
Right now, he only wanted to meet her strength head-on.
Chika had shifted from Water Breathing to Hinokami Kagura — the Dance of the Fire God.
Her aura exploded, body temperature rising, eyes burning like twin suns.
Phase Two — begin.
She raised her sword, flame curling around her like living light.
Her lips moved softly:
"Hinokami Kagura: Phantom Sun Rainbow."
In Rengoku's vision, her figure vanished — no, melted into the heat of her own fire.
Even his sharp dynamic vision couldn't track her.
Left? Right? Above? Behind?
He pivoted sharply, blade ready — but the instant he turned, he realized—
Wrong direction.
Because behind him, where his guard had just been open—
Chika stood.
Her crimson eyes gleamed with divine intensity, her blade descending like the wrath of the sun.
"Hinokami Kagura — Tenth Form: Radiant Blessing!"
The flames erupted.
They roared like a living beast, surging upward as if to swallow heaven itself—
And the arena was engulfed in a torrent of fire and light.
BOOM!!!