Akira finally received the update about Erika's situation through his sister.
"So you're saying she got so caught up in the fight that she forgot to inform me about Upper Moon One?" he asked telepathically.
There was a brief silence.
"…Yes," Selena replied.
Akira paused for a moment before thinking back, "Then how is she doing now? Does she need any help?"
"No," Selena answered. "She's fine. More Hashira are gathering at her location now. The best thing you can do is search for Muzan. If he wakes up too soon, things will get very bad."
Akira frowned. "But wouldn't it be better if I go beat Kokushibo first, then wait for Muzan to wake up? If we deal with Upper Moon One quickly, wouldn't everything be easier afterward?"
"No," Selena replied immediately. "Unlike in the original story, Muzan didn't absorb Tamayo. The poison dosage inside him is lower. That means he might wake up much sooner than before. It's better for you to deal with him before he causes serious damage."
Akira hesitated. "But Kokushibo is strong. Even in the original story, so many Demon Slayers died fighting him. Wouldn't it be safer if I beat him first, then we all go after Muzan together?"
Selena went quiet for a moment before replying flatly, "You just want to learn Moon Breathing, don't you?"
Akira fell silent.
"…Yes," he admitted.
Selena sighed. "Seriously, brother."
"It's the only Breathing Style I haven't learned yet, Akira replied stubbornly. I want to learn it.
It's not that important," Selena said.
"It is important," Akira insisted.
Selena sighed again. "How about this? I'm already recording the fight. You can watch it later and learn from it. What do you say?"
Akira frowned. "How am I supposed to learn how he breathes just by watching a video?
That's the best I can do, Selena replied. Besides, Moon Breathing is basically discount Sun Breathing. I'm sure you can figure it out just by watching."
Akira hesitated again. "But wouldn't it be better if I were there? I'm still worried about Erika."
"Don't worry about her," Selena said firmly. "She'll be fine. Letting her fight stronger opponents is good for her growth. You can't always protect her."
Akira let out a quiet sigh. He knew she was right.
"…Fine," he finally said.
Just then, two figures rushed toward Akira and Yushiro.
"Oh, you guys are late," Akira said casually.
It was Mitsuri Kanroji and Obanai Iguro, who had just arrived.
Akira couldn't help but think, "Why does Mitsuri always arrive late to battlefields?
This was already the second time she was late to a fight involving an Upper Rank Four."
Mitsuri, completely unaware of what was going through his head, hurried over and asked anxiously,
"Akira-kun! How are you? Are you okay?"
"Mitsuri-san, don't worry. I'm fine," Akira replied calmly.
Obanai's gaze shifted past Akira. He narrowed his eyes and asked, pointing toward Nakime, whose head Yushiro was gripping, talismans spread across her face.
"What happened to that demon?"
Akira followed his gaze.
"That demon controls this place. She's the new Upper Moon Four. Yushiro has taken over her senses, so now he can control her."
Obanai looked visibly impressed, then his expression sharpened as another thought crossed his mind.
"Then where is Muzan? Have you found him?"
Akira shook his head.
"Not yet. We're still searching for him."
At that exact moment, Yushiro spoke.
"…Found him."
Akira, Mitsuri, and Obanai all froze.
Akira turned sharply toward him.
"Found who?"
Yushiro answered without hesitation,
"Who else? Muzan. I found him."
Inside the Demon Slayer headquarters, the Ubuyashiki children continued their work.
All five of them sat around a large table, talismans affixed to their foreheads, hands moving rapidly as they drew and updated the ever-expanding layout of the Infinity Castle, relaying commands based on the information flowing in.
Suddenly, the atmosphere changed.
Ubuyashiki Kiriya, the current head of the Ubuyashiki household, who had taken over because his father was too ill to lead, froze mid-movement.
"…Muzan....we found him."
The words left his mouth as his eyes widened in shock.
One of the Ubuyashiki daughters, seated at another drawing table, immediately spoke up.
"The first team is about to arrive. The second team is right behind them."
Kiriya's face drained of color.
"Wait, don't send them!" he shouted. "Stop them!"
The girl blinked. "Huh?"
"Don't send them to where Muzan is," Kiriya commanded urgently. "Have them stand by until the Pillars arrive."
But even as he spoke, he knew.
It was already too late.
The Demon Slayers had already arrived there.
In the midst of multiple randomly arranged tatami rooms, something grotesque hung suspended in the air.
A massive cocoon of flesh, supported by thick, sinewy growths, was anchored to the surrounding rooms like a grotesque spider at the center of its web.
One of the Demon Slayers swallowed hard.
"…This is it. We found it. It's Muzan."
Another stared up at the cocoon, unease creeping into his voice.
"Our swords won't reach it. What should we do?"
"Calm down," someone else said quickly. "First, let's cut off all these flesh legs from every direction."
Just then, another Demon Slayer hurriedly interjected,
"Wait, hold on a minute. We received an order to stand by."
"This isn't a situation where we can wait," someone snapped back. "We don't know what will happen before the Pillars arrive..."
Before he could finish his sentence.
The flesh cocoon ripped open.
A figure burst out of it in an instant, crossing the distance faster than any of them could react.
The Demon Slayer who had been speaking was struck first.
Before anyone could even blink, his entire upper body was obliterated, scattering blood and flesh across the tatami rooms.
Only then did everyone finally understand.
"…Muzan."
Yes, it was Muzan.
But he looked nothing like before.
He no longer resembled the man dressed like Michael Jackson.
Now, he looked like the demon he truly was.
His hair grew longer, turning stark white.
Numerous mouths opened across his limbs, each lined with rows of impossibly sharp teeth.
Dark red, scale-like masses spread across his arms, his forehead, and his entire lower body.
He had entered his full demon mode.
One of the Demon Slayers screamed,
"It's Muzan...he's here...!"
The scream cut off mid-sentence.
His body was blown apart before he could finish.
Then Muzan moved.
In a single blur, he dashed across the room.
One by one, Demon Slayers were torn apart, their bodies ripped, crushed, shredded, before they even realized what was happening.
Above them, a Kasugai Crow screamed desperately, relaying Kiriya's orders.
"Everyone fall back! Wait for the Hashira to arrive! You are just going to be food for his recovery!"
Muzan looked up briefly.
"They are all dead."
In the very next moment, the crow was decapitated, its voice silenced.
Muzan's lips curled faintly.
"After living for a thousand years, I lost my sense of taste," he said calmly.
"But now that I am starving…"
His gaze swept over the carnage.
"…it's very delicious."
A low chuckle followed.
"You are deliberately bringing me food. My compliments, Ubuyashiki."
Back at the headquarters, Kiriya reacted instantly.
"Get the second team to retreat," he commanded sharply. "Do not go near Muzan. If he eats even one more member, he'll only recover faster."
His eyes hardened.
"Send word to all the Hashira. Muzan has awakened."
The order rippled outward.
Across the Infinity Castle, the message spread at once. Hashira who were not currently engaged in battles against powerful demons immediately changed course, rushing toward the location where Muzan had appeared.
At the same time, Akira received the news as well, in fact, he received it first.
Directly from Yushiro.
Still gripping Nakime's head, Yushiro spoke urgently.
"Muzan is awakened."
Akira froze.
So did Mitsuri and Obanai, who were standing beside him.
"…Where?" Akira asked.
Yushiro shot him a look.
"How exactly am I supposed to say where in the Infinity Castle?"
Akira clicked his tongue, realizing the problem.
"…Right."
Then an idea struck him.
"Then guide me to him," Akira said. "Or...wait. Can't you make her open a portal directly to where Muzan is? We can jump him."
He pointed at Nakime, who was still restrained under Yushiro's control.
Yushiro shook his head.
"I can't control her that much yet. I need more time."
He paused, then added,
"It would be better if you just get there on your own."
Akira exhaled once, steadying himself.
"…Alright then."
He raised his head.
"Raven. After you."
His Kasugai Crow immediately responded, wings spreading wide.
"Follow me!"
The crow shot forward, flying toward Muzan's location.
Without hesitation, Akira, Mitsuri, and Obanai took off after it.
On the other side of the Infinity Castle, Muzan moved.
He reached the second team in an instant.
Unlike the first group, this unit had already been warned. The moment they sensed his presence, they spread out and took their stances, blades raised, breaths steady. Fear was there, but so was resolve.
Muzan appeared before them.
"Heh," he sneered. "Trying to put up a fight?"
His crimson eyes gleamed with contempt.
"Tonight, I will eliminate all Demon Slayers. From here on, I will massacre every last one of you."
Then he vanished.
Muzan moved faster than their eyes could track.
The next moment, blood sprayed across the tatami rooms. Bodies were torn apart. Limbs flew. Screams were cut short.
But.
Not all of them fell.
A few Demon Slayers died instantly, their bodies destroyed before they could even react. Others were struck and sent flying, losing limbs or suffering grievous wounds.
And some.
Some were still standing.
Muzan halted mid-motion, his expression twisting in surprise.
"…What?"
Several Demon Slayers staggered but remained alive. Some were bleeding heavily. Some had broken bones. A few, astonishingly looked almost unharmed.
"How did they survive that?"
What Muzan did not know was this:
Akira had trained them for this exact moment.
Their brutal training with Luchan was not meant to win against Muzan. It was meant to survive him, to endure the first strike, to minimize fatal damage, to live through what should have been certain death.
The first team had been annihilated because they were caught completely off guard.
But the second team had time.
Time to brace.
Time to move.
Time to apply everything they had been drilled into them.
And that single difference.
Was enough to keep them alive.
But they couldn't hold out for long.
One by one, the Demon Slayers began to falter. Their breathing grew ragged. Blood soaked the tatami beneath their feet. Muzan stepped forward, his presence alone crushing their resolve.
He raised his arm.
"Enough."
Just as he prepared to finish them
Two attacks struck him at the same instant.
"Water Breathing, First Form — Water Surface Slash!"
A clean, flowing arc of steel cut through the air.
"Hinokami Kagura — Dance!"
Blades roared, twisting like a living sun.
Muzan was forced to shift his stance as the twin assaults reached him.
Tanjiro Kamado and Giyu Tomioka had arrived.
Muzan turned slowly, crimson eyes locking onto Tanjiro.
"Oh," he said calmly, almost amused.
"Kamado Tanjiro… you have finally arrived."
Tanjiro's face was twisted with fury, far more than usual. His grip on his blade trembled, not with fear, but rage.
He screamed,
"MUZAN!"
The battle truly began.