Just as Kokushibo was about to deliver the final blow, a blinding crimson light suddenly enveloped Erika.
The strike never reached flesh.
Instead, Kokushibo's blade crashed against something metallic, and an unseen force erupted outward, blasting him backward. His body was hurled away as though struck by an invisible wall.
When the crimson light faded, what stood in Erika's place was no longer her unprotected body.
She was clad in jet-black armor.
It was unmistakable.
Akira's Device—Eclipse.
The armor resembled a compact Gundam-like astray frame, sleek and angular, yet different from the one Erika had seen before. Its proportions were subtly more feminine, refined to fit her form, and where Akira's Eclipse burned with purple eyes, this one glowed a deep blue instead.
Despite those differences, there was no doubt.
This was Eclipse.
Erika stared down at her armored hands, shock flooding her mind.
"Th-That's… Akira's Eclipse, right?" she blurted out. "Why… why am I wearing it?"
Only moments ago, she had been certain she was about to die. And now she was standing inside Akira's device, without warning, without explanation.
Her thoughts spun wildly.
Then.
A sharp, sinking feeling gripped her chest.
It came without reason, without logic. A sudden, overwhelming dread, as if something terrible had happened far away. Her heart tightened painfully.
"Akira…"
She didn't know how. She didn't know why.
But she felt it.
Her voice trembled as she spoke telepathically.
"Selena… something happened to Akira, didn't it…?"
There was a brief pause.
Then Selena's voice reached her, heavy and grim.
"…Yes. Something did happen to him."
Erika's breath caught.
"W-What happened to Akira…?" she asked, her voice shaking.
Selena's voice reached Erika telepathically again, tense and heavy.
"This is bad… I knew this would happen eventually, but the timing is… unfortunate."
Erika snapped back immediately, her voice sharper than usual.
"What happened?!"
Selena let out a quiet sigh before answering.
"Listen, Erika-chan. The situation is extremely dangerous. We don't have much time. You need to kill him now and run to my brother."
Erika's patience shattered.
"What happened to Akira?!"
There was a brief hesitation.
Then Selena spoke.
"…He's going to die if you take too much time."
The words hit Erika like a blade through her chest.
"Akira… is going to die?"
Her mind went blank.
"Why…? How…?"
She couldn't accept it. She couldn't even imagine it. Akira was stronger than everyone, stronger than demons, stronger than fate itself. How could someone like him… die?
Her thoughts spiralled and were violently cut short.
Kokushibo's crescent moon blades slammed into her.
The impact rang out like thunder, metal grinding against metal as the blades struck Eclipse's armor. The force staggered her, but the damage was minimal, the armor absorbing the blow effortlessly.
Still, the impact snapped Erika back to reality.
Only then did she hear Selena's urgent voice again.
"Erika-chan! Get back to your senses…Erika-chan!"
"Huh…?" Erika muttered, her mind still dazed.
Selena's voice hardened, leaving no room for hesitation.
"You have to kill him now. And then you have to get to my brother. If you don't… he will die."
"But… how am I supposed to beat him?" Erika forced herself to think as she took in the battlefield.
Muichiro and Genya were struggling to get back to their feet. Sanemi and Gyomei were in far worse condition, bleeding, battered, their bodies pushed beyond their limits, yet even now, they were still fighting Kokushibo head-on. His attacks were overwhelming, each strike carrying enough power to end the battle instantly.
Yet many of those blows had been absorbed by Erika's ribbons, preventing them from becoming immediately fatal. Because of that, Sanemi and Gyomei managed to stagger back up again and rejoin the fight, refusing to fall.
Erika clenched her fists.
"This isn't enough. What should I do?" she asked telepathically, panic creeping into her voice.
Selena answered without hesitation.
"Right now, you're wearing my brother's armor. You can't use his Noble Arts without training, but you can use its passive abilities, super strength, and super healing. Combine that with your blood powers, and you can win. Hurry. There's no time."
Erika nodded sharply.
She would never let Akira die.
Her blue eyes turned crimson as she resolved herself. She had to finish this, and she had to do it fast, no matter what.
At that moment, Sanemi and Gyomei were blown away again by Kokushibo's relentless assault.
That was all Erika needed.
She launched herself forward.
The ground shattered beneath her feet as Eclipse's power surged through her body. In an instant, she crossed the distance between them and punched Kokushibo square in the face.
The strike landed before Kokushibo could even react.
His body was sent flying, blasted backward by sheer force alone.
Erika didn't stop.
She moved to follow up, instinctively reaching to summon her Device—
Églantine.
Nothing happened.
Her heart skipped.
Kokushibo crashed into the distance, skidding across the floor, but he recovered immediately, landing cleanly and straightening as if the blow had never happened. His six eyes locked onto Erika, now clad in the unfamiliar jet-black armor.
"Selena," Erika demanded telepathically, tension sharp in her voice. "Where is Églantine?"
There was a pause.
Then Selena replied, calm but firm.
"You can't use it right now. Just use Eclipse to beat him."
Erika's breath hitched. "How am I supposed to fight without it?"
Selena answered instantly.
"Remember, you're a vampire. Your greatest weapon is your blood. Use it. Don't worry about running out."
There was a brief pause before she added,
"Eclipse has passive super regeneration. Your blood will regenerate far faster than before, so you basically have infinite ammo."
Erika steadied her breathing.
Then she nodded.
She had never truly used blood manipulation before, like other vampires before, but there was no time to hesitate.
She had to defeat him, and she had to save Akira.
Drawing on every ounce of her vampire power, Erika extended her hand.
Blood began to flow freely from her palm, not spilling to the ground, but floating, gathering in the air as if answering her will. Eclipse's passive regeneration surged, replenishing what she lost almost instantly. In just a few seconds, an enormous sphere of blood formed above her, pulsing with power.
Across from her, Kokushibo took his stance.
His six eyes narrowed as he gazed at the massive blood sphere hovering overhead.
Erika moved first.
She hurled the blood mass forward at tremendous speed, the air screaming as it tore toward him.
Kokushibo instantly recognized the danger.
"Moon Breathing—Sixteenth Form: Moonbow, Half Moon."
With his altered katana, he swung outward. Six immense curved slashes crashed forward, each accompanied by countless crescent moon blades, their power so overwhelming they gouged craters into the ground as they advanced.
The crescent blades collided with the blood sphere.
The impact was explosive.
The blood ball burst apart, splattering violently in every direction and completely engulfing Kokushibo.
But Erika did not stop.
She raised both hands.
The scattered blood droplets froze midair.
Tiny crimson blood seeds formed all around Kokushibo, surrounding him from every angle.
"Blood Demon Art: Thousandfold Crimson Stakes."
In the next instant, the blood seeds detonated outward.
Gigantic blood spikes erupted in every direction, piercing straight into Kokushibo's body. They impaled his limbs, his torso, his shoulders, driving deep into his flesh. Once embedded, the spikes branched inside him, spreading like roots, locking his body in place and restricting his movement completely.
This was the same technique Erika had once used to restrain Muzan.
But this time.
There were hundreds more stakes.
The sheer number overwhelmed even Kokushibo. Though his strength was immense, breaking free would take time.
Time, Erika would not give him.
"Blood Demon Art: Exploding Blood."
Every blood stake piercing Kokushibo detonated simultaneously, erupting into brilliant pink flames that engulfed his body from within.
Yet Erika still didn't stop.
She clenched her hands tighter.
The scattered blood across the battlefield responded, surging back toward the burning mass. The pink flames twisted and converged, compressing Kokushibo into a single point. Erika poured even more of her blood into the attack, Eclipse's regeneration pushing her far beyond her normal limits.
The flames deepened in color.
Pink turned to dark crimson.
For several seconds, the pressure intensified, crushing, burning, condensing.
Then Erika finally lowered her hands.
She staggered slightly, breathing heavily.
When the flames faded.
There was nothing left.
Kokushibo was gone.
Not even a single trace of him remained.
Only ashes, drifting silently through the air.
Gyomei, Sanemi, Muichiro, and Genya, each of them freshly stabilized by Akira's blue potion, stood frozen in place.
They stared at the empty space where Kokushibo had been only moments ago.
Sanemi broke the silence first, his jaw slack as he muttered,
"…If she could do that, shouldn't she have started with it?"
Erika barely heard him.
Her chest rose and fell heavily as she struggled to catch her breath. Normally, using that much blood would have pushed her far beyond collapse; she would have lost consciousness long before the attack ended.
She is only standing here because Eclipse armor is actively restoring her stamina, blood, and knitting her strength back together piece by piece.
And just after restoring her to full health, the Eclipse armor disappeared.
Erika swallowed and spoke telepathically, her voice trembling.
"I did it…Now, where is Akira? What happened to him?"
Selena sighed.
"Well… he…"
She didn't get to finish.
A sound tore through the Infinity Castle.
It echoed through every corridor, every shifting room, low, primal, and impossibly deep. A sound like something ancient awakening after a long slumber.
Erika froze.
Her blood ran cold.
She knew that sound.
It was far too familiar.
Fear, raw and instinctive, clenched around her heart.
"…Selena," Erika whispered, her voice shaking, "that sound… how is that possible here…?"
Then realization struck her like a blade.
Her eyes widened.
"Wait…Akira."
Selena sighed again, this time heavily.
"…Yeah. That's what happened to him."
She didn't soften the truth.
"You have to hurry. If you don't, everyone in the Infinity Castle is in danger."
While Erika was locked in battle against Kokushibo, far away on another level of the Infinity Castle, a different scene lay frozen in blood and silence.
On a floor, stained deep red, Akira lay motionless at the center.
His body was… wrong.
Bones were shattered. Flesh was torn open in multiple places. Organs had been crushed beyond what any human body should have been able to endure. It was only because Akira's body had long since surpassed human limits that it still retained a recognizable shape at all.
Had anyone else taken that blow, there would have been nothing left to recover, only fragments scattered across the floor.
In the distance, Muzan stood staggering.
His body was regenerating.
Slowly.
Far too slowly for his liking.
The wounds Akira had inflicted still burned inside him, resisting his cells, forcing his regeneration to crawl instead of surge. Each attempt to repair himself met resistance, as if something foreign still gnawed at his very existence.
Muzan's eyes remained fixed on the broken figure on the ground.
Cold.
And faintly… afraid.
As if worried that Akira might suddenly wake up.
Yet Muzan himself was too weak to move now, to approach, to finish him off.
Scattered farther away, Mitsuri, Obanai, Giyu, and Tanjiro lay fallen.
All of them had been hurled away by Muzan's earlier energy shockwave, their nervous systems severely damaged. Muscles screamed in agony. Lungs burned with each shallow breath. Limbs refused to respond the way they should.
Tanjiro forced his head up.
His eyes widened in horror as he screamed.
"Akira-san…!"
And then.
Something happened.
A translucent blue light flickered into existence above Akira's shattered body.
A holographic screen unfolded in midair, layers of glowing text and rotating diagrams cascading rapidly as it scanned him from head to toe.
Structural integrity: critical
Vital systems: catastrophic failure detected
Damage exceeds acceptable survival threshold
Emergency protocol activated
Override authorization: confirmed
Releasing control art restrictions — Level: Zero
The blue light intensified.
Chains of light suddenly manifested around Akira's body, binding him tightly, only to shatter like glass an instant later.
Under the stunned gazes of everyone present, Akira's body moved.
Bones snapped back into place with wet, grinding sounds. Torn muscle fibers knitted together at impossible speed. Flesh reformed as if time itself were being forced backward. The blood flowing freely from his wounds halted, then vanished as his skin sealed shut.
Akira pushed himself upright.
He staggered.
His breathing was ragged and uneven, as though something inside him was tearing violently against its restraints. His hands clenched and unclenched, fingers trembling uncontrollably. Veins bulged beneath his skin, glowing faintly with a violent purple hue.
Pain twisted his expression, well, not exactly pain since he is basically immune to it, but his expression did twist.
As if he were holding back something vast.
Something angry.
Slowly, he turned his head.
His eyes found Tanjiro and the others.
With the last of his remaining consciousness, Akira spoke.
"…Run."
The word was barely audible.
Then Akira lost consciousness and collapsed forward.
And then.
The transformation began.
Akira's spine arched violently, bones cracking as his skeletal structure elongated. Muscles expanded and reshaped, swelling with monstrous density as his body was forcibly rewritten. His fingers curled inward as nails lengthened, blackening and sharpening into claws that gouged deep grooves into the castle floor.
White fur burst from his skin in violent waves, spreading across his arms, shoulders, and back, swallowing his body whole. His jaw forced itself forward, teeth reshaping into long, predatory fangs as his skull restructured with brutal finality.
His chest expanded.
Once.
Twice.
Then he rose.
No longer human.
A towering werewolf stood where Akira had fallen, its fur pure white, thick, untamed, and rippling with raw, overwhelming power. Its eyes burned a deep, luminous purple, filled with feral madness that crushed reason beneath instinct.
The creature threw back its head.
And howled.
A primal howl, its sound tore through the Infinity Castle, shaking walls, rattling platforms, echoing endlessly through corridors that twisted beyond comprehension. Demons across the castle froze in terror as the howl reached them, instinct screaming danger into their very cores.
It was the cry of a beast long restrained.
A slumbering beast has finally awakened.