Rengoku and Chika exchanged a brief, sharp glance—a silent understanding between warriors.
Akaza, busy preaching his gospel of immortality, didn't notice. And even if he had, he probably wouldn't have cared.
"Rengoku! Chika! Become demons—become my comrades!"
"I refuse!"
Rengoku's voice thundered like a blade through the air.
He leapt backward, Nichirin Blade blazing with resolve.
"Flame Breathing, Esoteric Art – Ninth Form: Rengoku!"
Fighting spirit surged through him, igniting in perfect harmony with his sword.
The flames he unleashed roared like hellfire—bright, consuming, absolute.
Akaza's golden eyes widened as he felt it—Rengoku's fighting aura suddenly rising to a new height.
Excitement lit up his face. He dropped his stance low, muscles tightening with electric anticipation.
"Destructive Death: Annihilation Type!"
Power gathered in his fists, his entire being trembling with joy.
He lived for this—pure, frontal combat. No tricks, no hesitation, only strength meeting strength.
"Excellent, Rengoku! I knew it—you're the one! Come! I'll show you the power of demons! Once you've tasted it, you'll understand!"
He stomped the ground.
BOOM! The earth split beneath his feet as his body blurred forward like a blue meteor streaking through the night.
Rengoku inhaled deeply, his lungs burning with the heat of his own flame.
He didn't rush forward immediately.
He waited—waited for that single instant when Akaza closed the distance.
And then—
Every ounce of power in his body condensed into his grip.
A crimson spark lit at the base of his sword.
Red Blade—Hekiken.
The reddish glow raced up his weapon, searing through the air.
Akaza froze mid-charge as a violent premonition slammed through his instincts.
What—?! This aura… it's not his energy… it's coming from the blade?!
The demonic senses within him screamed.
The sword—its presence multiplied, radiating pure, blinding hostility toward all demonkind.
If that blade touched him, it would be bad. Very bad.
Akaza reacted instantly, his battle instincts shrieking warnings.
He slammed both feet into the ground, forcing himself to stop short.
But Rengoku was faster.
In a single explosive step, he closed the ten-meter gap and brought his flaming blade down in a vertical arc of death.
Akaza's Compass Needle activated automatically. His body twisted, slipping past the descending strike by the smallest of margins.
Yet before he could recover—
"Shh."
A whisper, a flicker—Chika appeared behind him.
Compass Needle wasn't omnipotent. It could predict, but not everywhere at once.
Between Rengoku's blazing pressure and Chika's killing intent closing in from behind, Akaza had to choose.
Front—or back.
He knew he'd be hit at least once.
And no matter how he measured it, the greater danger lay ahead.
That red-hot blade—everything in him screamed avoid it.
He pivoted, evading Rengoku's second slash, then spun toward Chika, fist tightening.
If he had to lose an arm, so be it. He could regrow one faster than a breath.
But when his fist met her sword—Chika smiled.
"Got you."
Her Nichirin Blade wasn't crimson yet. It looked ordinary, gleaming faintly under the moonlight.
And then—
From the base of the blade, a faint scarlet glow began to creep upward.
In just over a second, her sword was fully awakened—a red-black Nichirin Blade, flame and shadow entwined.
When her blade and Akaza's fist collided, the world flashed red.
Agony exploded through his arm.
Pain.
Real pain.
His mind jolted—and then something else surged forth.
A memory that wasn't his.
A man with brown hair and solemn eyes stepped through the haze of his mind, gripping a sword identical to Chika's.
The red-black blade gleamed like blood in sunlight.
The vision flickered twice—then deepened, dragging Akaza's consciousness somewhere far beyond himself.
"What are you so proud of? What joy is there in this?
You call this living?! What have you turned life into?!"
That voice—calm, furious, righteous.
The man ran forward, blade burning brighter than anything Akaza had ever seen.
This… this memory… it's Lord Muzan's?!
Akaza's thoughts snapped back into his body with a violent shudder.
Pain shot through him where Chika's blade had cleaved into his arm.
Pain. True, searing, human pain.
He hadn't felt that in over a century.
Snarling, he tore himself free, abandoning the severed arm and leaping back to escape their encirclement.
He panted heavily, staring at the stump that refused to regenerate.
He willed it—commanded it to heal—
but the flesh crawled sluggishly, slower than it ever had before.
"This sword… suppresses regeneration?"
Disbelief and horror flickered across his face.
He'd never experienced anything like it. Not in all his long, brutal years.
And that memory—those emotions—those were not his own.
They belonged to Muzan Kibutsuji.
At that very moment, deep within the Infinity Castle, Muzan himself convulsed.
His pale face turned a ghastly shade of white as he trembled uncontrollably.
Through Akaza's mind, he had seen her—
that girl wielding the same blade as Tsugikuni Yoriichi.
So it was true.
The scar on the wall… the mark he'd seen before…
The user of the Breath of the Sun still existed in this era.
The same breathing style.
The same sword.
The same accursed presence.
His cold voice hissed through Akaza's mind like a serpent:
"Akaza."
Akaza stiffened.
"Lord Muzan."
The Demon King drew a long, shaking breath before forcing his tone into calm authority.
"Use all your strength," Muzan ordered coldly. "Destroy every Demon Slayer before you—especially the one wielding the red-black Nichirin Blade."
His words carried the unshakable command of absolute dominance.
Even the Upper Moons could not resist it.
Normally, Muzan tolerated Akaza's odd code of honor—his refusal to harm women.
But now was no time for such indulgence.
Under Muzan's direct control, Akaza's eyes darkened, their gold laced with crimson.
His will bent, his sense of self shifting as Muzan's influence overwrote it.
In that instant, Chika ceased to register as "woman."
She was only an enemy—a threat to Muzan.
Akaza's breathing deepened, his expression settling into grim resolve.
He stomped the ground.
A twelve-pointed sigil flared beneath his feet, blue energy spiraling outward.
"Such a pity…" he said softly, raising his fists. "But you both must die."
"Destructive Death—Compass Needle!"
The earth split once more, the battlefield igniting in light and shadow as the Upper Moon unleashed his full fury.