Erika tore through the twisting corridors of the Infinity Castle, flying straight toward Akira's location.
The moment Kokushibo fell, she had taken off without a word, leaving everyone behind in shock.
The others should have heard what happened by now; Kasugai crows would already be spreading the news, but Erika didn't slow down. She was moving so fast that her own Kasugai crow, Rose, who was supposed to guide her, was struggling to keep up, reduced to a distant shadow behind her.
If not for Selena guiding her telepathically, she might have lost her way in the ever-shifting corridors.
For her, right now, nothing is more important than Akira.
As she flew, Erika demanded, "Selena, what the hell happened to Akira?"
There was a brief pause before Selena replied.
"Well… he turned into a werewolf. Remember, he had lycanthropy. That's what happened."
Erika's heart skipped.
"But he said he cured it, right? she shot back immediately. He didn't transform even once, not even during full moons."
"That's true," Selena answered calmly. "He did cure his lycanthropy, but he kept the power of the curse as a secret emergency backup."
"What emergency?" Erika asked, her voice tight.
Selena answered without hesitation. "When he's fatally injured, the curse activates. He turns into a werewolf."
Erika's breath caught.
"The transformation and the werewolf's healing factor repair his body and save his life," Selena continued. "But in exchange, he loses control. He goes berserk, because all the animalistic instincts he sealed away until now come flooding back at once."
Erika clenched her fists mid-flight. "Then why was he fatally wounded?"
Selena hesitated.
"I… don't really know how to say it, to be honest."
"Just say it bluntly," Erika snapped.
There was a small sigh on the other end.
"Fine. He was fighting Muzan. He was about to land the finishing blow, then his Eclipse armor suddenly disappeared. Muzan used that opening and launched an all-out, desperate attack."
Erika's voice trembled. "Did it disappear… because of me?"
"Don't beat yourself up," Selena said immediately. "That idiot got hurt because he got cocky. He relied too much on the armor and wanted to show off. If he'd stayed sharp, even without Eclipse, he could've dodged that attack with his speed, and I'm sure he learned his lesson after suffering this loss."
Erika didn't respond right away.
Then she asked quietly, "Then why did Eclipse disappear from Akira… and appear on me?"
"Because the Sacred Gear, 'Lunar Vow' has finally awakened," Selena replied.
"Huh?" Erika blurted out, genuinely confused.
"Well, after you two reunited," Selena explained. "You kept growing closer and closer, right. You drink his blood every day. Lunar Vow was already on the verge of awakening; it just needed a trigger. And you being in mortal danger was that trigger. It activated and forcibly switched your devices to save you."
Erika frowned.
"It can… switch our devices?"
"Apparently, it can," Selena said. "Though, honestly, we'll need a lot more testing to figure out what else it's capable of."
Erika nodded, then asked with hesitation.
"So… he's okay, right? He's not going to die, right?"
There was a brief silence.
Then Selena spoke gently. "Sorry, Erika-chan. I said that earlier to make you hurry."
Erika's heart skipped.
"My brother is alive," Selena continued. "And physically fine. But he's completely out of control right now. If we don't get there fast, every Demon Slayer in the Infinity Castle is in danger."
Erika swallowed. "Is it really that bad?"
"Yes," Selena answered without hesitation. "He modified his werewolf transformation with a few… special abilities. Believe me, right now, he's on an Avengers-level threat, so we need to get there faster."
Erika didn't reply.
She simply flew faster, pushing herself beyond her limits.
No matter what it took, she wouldn't let anything bad happen.
On the other side of the battlefield, Tanjiro stared in shock.
Akira, who had been on the verge of death only moments ago, suddenly changed.
White fur burst from his body as his form twisted and expanded, reshaping into a towering, humanoid wolf. A primal howl tore from his throat, its sound shaking the Infinity Castle itself.
Tanjiro's breath caught.
"That's…a werewolf."
He knew exactly what it was.
Akira had told him stories about it before.
Right now, Akira had turned into a werewolf.
Nearby, Muzan, who had been in the middle of regenerating, froze. His eyes widened as he stared at the creature before him. He knew Akira was not a demon, but then what was this?
For the first time in a very long while, fear crawled up Muzan's spine.
As his regeneration continued, his instincts screamed only one thing.
Run.
But the moment Akira finished howling, the werewolf lowered his head.
Those glowing eyes, filled with raw, murderous intent, locked onto Muzan.
Akira was no longer in control. He would attack anything in his path.
But before anything else.
Before anyone else.
He would destroy his enemy first.
In a blink, Akira vanished.
The next instant, He reappeared directly in front of Muzan.
A single swing of his claws followed.
Muzan's head exploded, shattered into fragments as his body was launched backward, slamming violently into a wall and cracking it apart.
Silence followed for a fraction of a second.
Then, as his body slid down the ruined wall, Muzan's head regenerated immediately, flesh knitting itself back together as his eyes snapped open once more.
But Muzan didn't even have time to react.
Akira was already on him again.
The werewolf closed the distance in an instant and punched him.
Muzan's head was destroyed once more, his body ripped free from the wall and hurled backward, crashing through another wall, then another, then another, tearing through multiple rooms of the Infinity Castle before finally slamming into yet another wall and collapsing to the floor.
Once again, Muzan's head regenerated.
But this time, panic flooded his thoughts.
"What… what the hell is that?That's not a demon.It's a monster…something I've never felt before…, and it's strong."
Fear, sharp and undeniable, set in.
"I need to get away from here."
But even as the thought formed, Muzan realized the truth.
"This wolf is faster than me.And I can't divide either…"
His options narrowed to a single path.
"Then my only chance is to fight it."
Muzan transformed into his full combat form.
His arms twisted and elongated into whip-like appendages. His legs reshaped, built for explosive speed and power. From his back, nine whip-like tentacles burst forth, writhing with lethal intent.
As Werewolf Akira charged straight at him, the whips from Muzan's arms and back lashed out like a cyclone, tearing through the air from every direction.
But Akira didn't slow down.
He didn't dodge.
He didn't block.
He tanked the attack.
The strikes slammed into his body, but his thick white fur absorbed most of the damage, and whatever injuries did break through healed instantly.
Closing the remaining distance, Akira reached out, grabbed one of the tentacles, and yanked Muzan toward him.
Claws dug into him, holding him in place.
Then Akira bit down hard on Muzan's shoulder, ripping out a chunk of flesh.
Thankfully, he didn't swallow it.
Because it tasted awful.
Muzan tried to pull away.
But Akira, now furious after tasting something so bad, smashed him to the ground.
Once.
Twice.
Again.
And again.
And again.
The Infinity Castle trembled under the relentless blows.
Muzan was furious.
"How dare this animal attack me."
His rage twisted instantly into violence as Muzan forced the bones within his body to erupt outward, shooting through his flesh like a porcupine's spines.
The sudden counterattack finally made Akira step back, if only for a moment.
Muzan seized the opening.
All across his body, mouths split open, rows of sharp teeth gnashing as he unleashed a violent energy shockwave.
The blast slammed into Werewolf Akira, staggering him backward. His nervous system jolted violently, his movements slowing for just a fraction of a second.
But he recovered almost immediately.
Still, that brief pause was enough.
Muzan retreated, putting distance between them as his body regenerated from the damage. Yet horror crept into his thoughts.
"My regeneration… It's slower."
At the place where Akira had bitten him, distinct teeth marks still remained, refusing to heal properly.
Even so, Muzan forced his flesh to swell and reshape, forming a massive fist of condensed muscle, and punched Akira as he charged forward.
Akira punched back.
The collision sent both of them flying, their bodies blasted away in opposite directions. They crashed into the castle, skidded across shattered floors, and then rose again.
Akira lunged first.
Muzan raised both hands. They expanded grotesquely, huge mouths opening in the centers of his palms as he fired continuous shockwave blasts straight at the charging werewolf.
Akira didn't dodge.
He charged through the barrage, tanking the hits head-on. Each blast slowed him slightly, battered his body, and rattled his nerves.
But he kept coming.
Seeing Akira still advancing, Muzan pressed his hands together. Flesh fused, swelling outward, forming a single massive cannon of living muscle.
With a roar, Muzan fired his largest, most concentrated shockwave yet.
The blast struck Akira head-on, launching him backward, smashing him into the castle wall, and burying him deep within it.
But Akira stood back up.
Muzan didn't stop.
He began forming an even larger arm cannon, bigger than before.
This time, Akira didn't rush forward.
Instead, he planted his feet.
He inhaled.
The air around him warped, dragged toward his chest as if the world itself were holding its breath. His lungs expanded far beyond natural limits, energy building within him.
Muzan released his shockwave, one larger than anything before.
And to counter that, Akira howled.
A purple ripple of sonic force exploded outward from his mouth, a devastating sonic wave that met Muzan's attack head-on.
Muzan's shockwave was completely overwhelmed.
The sonic howl shattered Muzan's arm cannon, tore through his flesh, and slammed into him directly.
Under the crushing force of the sound waves, Muzan's body destabilized, chunks of flesh disintegrating bit by bit.
And when his legs were destroyed.
He was unable to withstand it any longer, and what remained of his body was launched away, crashing through multiple walls before disappearing deep into the Infinity Castle.
The castle shook as silence followed.
Naturally, Muzan was not dead.
Though the rest of his body had been completely destroyed, only his head remained, torn apart from everything else, yet it refused to die.
However, something was wrong.
His regeneration, once absolute, was now agonizingly slow.
Cells struggled to divide. Flesh refused to knit together properly. The damage inflicted upon him lingered far longer than it should have.
Unable to regenerate a body in time, Muzan forced his head to adapt.
From beneath it, spider-like legs of flesh sprouted, stabbing into the ground and lifting his severed head upward. With frantic desperation, he began to crawl away, skittering through the shattered corridors of the Infinity Castle.
His instincts screamed one thing above all else.
Feed.
If he could consume the body of even a single Demon Slayer, he could regain enough strength to recover.
So driven by that desperate hunger, Muzan fled, for now.
Back to Werewolf Akira.
After blasting Muzan deep into the Infinity Castle, the beast did not calm down.
If anything, it grew more enraged.
The prey had escaped.
Its massive body tensed, claws digging into the shattered floor as it lifted its head and let out a low, feral growl. The murderous intent radiating from it did not fade; instead, it searched.
It needed more prey.
Slowly, the werewolf turned its head, eyes glowing with violent purple light as it scanned its surroundings for the next target.
And then.
It saw them.
Tanjiro, along with the Hashira, who had recovered enough to move, were rushing toward the battlefield.
But to the werewolf.
New prey had appeared.