Muzan's head popped out of his neck instantly.
But the instant regeneration failed to bring the arrogance back on his face.
Instead, a terror, the likes of which couldn't be seen, but only felt, had appeared in the Demon King's eyes, his bloody, slitted pupils shaking as his mind replayed the event of losing his head.
Failed.
Time after time, he failed.
Muzan couldn't recall when and how he had lost his head.
He couldn't remember who had attacked him and with what.
Forget about remembering the attacker; he couldn't even recall having a single rational thought just before losing his head. It was like, at some time before losing his head, he had stopped… thinking.
But it wasn't the case with the others.
Muzan found an answer in the terribly shocked faces of the Hashiras.
The same shock that had even made the two creatures — a black-suited, winged beauty and a bronze-armored knight — come out from the shadows they had been hiding in.
If the enemies' emotions weren't enough, Muzan didn't even need to see the same terrifying astonishment hammering his Moons' consciousness as he was connected to them closer than ever.
They, the Demon Slayers, the two abominations, and his Demons, had seen a man.
They had seen the man blinking in and out of existence, leaving behind not even a hint of his attack.
They had seen how that man had refused to open his eyes before uttering a row of words, as if he had looked down upon the very act of attacking him.
Him…
The Demon King…
The strongest existence in the entire world… almost an Immortal…
[Leave!] The voice in Muzan's head roared, losing the conniving charm it had always carried. [Leave right now!]
The voice.
He had come so close to achieving all that he had ever desired because of it.
Not only that, but his ambitions had already taken a drastic, higher turn, going beyond the mere ability to exist in the Sun.
To become a true Immortal.
To become a… God — the God of Death!
At first, when the voice had contacted him, Muzan had thought that he had begun losing his mind because of some unknown mutation.
It had troubled him so much that he had almost confined himself.
But, no.
The voice hadn't been just mere words into a troubled mind.
The voice turned out to be a prophetic guiding force.
It was this voice that had revealed Akaza's killer.
It was this voice that had told him the true significance of that demon's presence in this world. The outsider; an alien who had decided to support the Demon Slayers, instead of acting on his true nature.
The voice had also revealed this alien's intention for the world.
The alien didn't want a world of demons, despite being one himself.
The future that the alien was shaping for this world had no place for the demons who had existed in this world for centuries.
Even then, Muzan hadn't believed the voice.
But the Upper Moon Six met a dark fate then, letting him know that it was as real as things could get.
If it weren't for the voice, Muzan would have never known what truly happened to Dabi.
He would have never learned how to avoid getting his existence sealed.
The voice's generosity hadn't been without a price, Muzan had believed.
However, he had also believed that whatever it wanted from him, through him, needed him to get stronger… much, much stronger.
And, so, he had accepted going through the procedure which the voice had suggested.
Entity Pupation.
To be broken down into the tiniest particles, over and over again, attaching his existence to the world simultaneously…
It had taken him months.
Months in which the alien had killed Upper Moon Five and Four as well.
But, by that time, while pupating… evolving… becoming stronger and mightier… Muzan had already begun learning about his new abilities.
The ability to resurrect the dead. Not resurrect, but recall — almost reincarnation — the original soul, from the past to the present.
Source Recall — the voice had named it.
An ability that he could repeat over and over, never losing his momentum against any threat.
And Source Recall, despite being the most complex, restricted, and shocking one, wasn't the ability that Muzan had loved the most — the ability to become a God!
All Muzan needed, as the voice had put it, was to consume the alien's child.
That's it.
Once he had done that, eliminating the Demon Slayers in the process, nothing could prevent him from becoming — DEATH!
Nothing.
Or so he had thought.
Or so the voice had thought.
Now, the same voice was roaring in his mind to… abandon the battlefield.
Veins, as thick as fingers, popped on Muzan's head, throbbing visibly.
He could taste the threat around him; a threat that even he, despite all that had happened, had failed to perceive.
The next blade landing on his neck might be… Nichirin.
An evil grin manifested on Muzan's lips, his skin changing colors between pale white and blackish-red as if he were struggling with the idea of crushing all and everything or leaving.
And, just as the stunned Hashiras could act on that struggle, wielding their swords with an intention to die, the Demon King took a long breath, calming his nerves.
"You will regret not going for the kill…" Muzan said, blurring, as if he was speaking through an afterimage. "… because, by the time I come back, I will be…"
The Demon Slayers stared at the empty patch of earth where the Demon King had been standing.
Then, slowly, they looked up, their gazes landing on the Demons.
The Upper Moons stared back, but, ultimately, they blurred out as well.
The filthy sea of demons receded like a tide, the red moon in the sky regaining its silvery appearance.
The hundreds of Demon Slayers' shoulders relaxed.
Some even fell to their knees.
Not the Hashiras.
Not the group of Tanjiro, Nezuko, Kanao, and others.
Because there was one demon who was still standing on the field, so straight, as if he wanted to start the war all by himself… and win it, if he could.
"I asked…" Akaza repeated. "Where is Kai Stormborn?"