Mikazuki stared at the crisscrossing, fantastical space before him, a trace of emotion rising in his chest. "So this is the so-called Infinity Castle. It really is magnificent."
"You're surprisingly calm," Akaza finally gave Mikazuki a proper look. "Aren't you afraid at all?"
"Afraid?"
Mikazuki shook his head with a light chuckle.
"The day I joined the Demon Slayer Corps, I'd already prepared myself for death. If you're ready for it, what is there to fear? If you truly admire me, you might as well throw my corpse back to the Wisteria House."
"That won't do. With Akiwa around, cleaning up afterward would be a hassle~" Doma said lazily. "After all, no matter how you look at it, she's someone with a rather troublesome Blood Demon Art~"
Mikazuki turned his gaze to Doma. "Akiwa… you mean Hiru, right?"
"Who knows~" Doma gently waved his folding fan. "Strictly speaking, demons don't have gender~ So to me, she's Akiwa~"
"Even if it sounds strange coming from me…"
Mikazuki frowned.
"I'm already as good as dead. There's no need to try to sow discord between us with baseless claims."
"Ah…" Doma's eyes filled with pity, his seven-colored pupils shimmering with tears. "How pitiful. You've been deceived, just like that girl… What a tragic soul."
"Tsk—you Demon Slayer Corps really are naive," Akaza scoffed, the malice in his grin nearly spilling over. "Even though I can't stand this guy, he isn't lying to you this time. How ridiculous. The Demon Slayer Corps actually made a demon into a Hashira and trusts him this much… What a joke."
Caught between Doma's pitying gaze and Akaza's mocking stare, Mikazuki froze completely.
[If Hiru is a demon, then what about Yoriichi—and that 'big brother' they mentioned… No. In the end, how could a demon possibly overcome sunlight and wisteria? I need to stay cautious. I can't fall for this.]
"But you seem very close to Akiwa~"
Doma smiled again.
"How about becoming a demon yourself? That way, when we capture Akiwa, we'll get to see a very interesting expression on his face~ An old friend turning into a demon… Wouldn't that remind him of Black Kokushibo-sama? He'd be shaken to the core, wouldn't he? I can't wait~"
Mikazuki didn't answer, merely following the two demons in silence as they climbed step after step.
"Why so quiet? Akaza-sama may be cold, but I love chatting~ Won't you talk with me a little more? I'll make sure you die without regrets~ Isn't that considerate?"
"I have nothing to say to demons," Mikazuki lowered his head, his eyes resting on the frost between the scabbard and the guard of his blade. "And I won't become one."
"Oh my, how cold—"
Doma was about to continue when he suddenly stopped. A captivating smile spread across his handsome face.
"How lucky you are~ The Lord intends to see you~"
Mikazuki's brow knit tighter.
[The Lord? Muzan Kibutsuji? Why would he want to see me? If he intended to meet me, he could've said so from the start. Why the sudden change? …Right. That ice demon said I was friends with Hiru. But why would—could it be they weren't lying about Hiru being a demon?]
"Oh dear, what a dilemma~ I didn't expect the Lord to value Akiwa so highly~"
Doma sighed theatrically. "I was hoping to ask him to leave her with me as a friend~"
"Akiwa, Akiwa—enough already," Akaza said irritably. "Are you really that proud of being used as a hand warmer?"
"Of course~ Even if I can't remember it anymore, Akiwa didn't lie about liking me~" Doma propped his face in his hands. "If I could, I'd love to carry her around as a hand warmer too~ I'm sure we'd have plenty to talk about~"
Mikazuki paid no attention to their exchange.
He looked at the solid ice clinging to his Nichirin Blade, let out a nearly imperceptible sigh, and slipped his hands into the wide sleeves of his haori.
"So you've given up resisting? How pathetic."
"I'm not arrogant enough to think I could escape while facing at least three Upper Moon demons," Mikazuki said calmly, lowering his gaze to meet Akaza's golden eyes. "Especially when none of you look particularly strong. Besides, instead of flailing around and embarrassing myself in front of you, I'd rather use the fact that you want something from me to disgust you a little."
"That sharp tongue really does resemble Akiwa," Doma laughed as the muscles in Akaza's face began to twitch. "I can't wait to see Akiwa's expression when he hears of your death~ It'll be quite a spectacle~"
"Your idea of 'liking' someone is truly twisted."
This time, Doma simply smiled and continued fanning himself without replying. After a sharp clang, Akaza vanished from sight.
After passing through another corridor, Mikazuki finally saw the demon whose Spatial Blood Demon Art formed the Infinity Castle.
She was a small, female demon with long hair covering her face, cradling a biwa in her arms. She sat against the wall, and behind her, her pitch-black hair climbed upward like creeping vines.
Mikazuki lowered his gaze to Nakime, still standing with his sleeves drawn together, his thoughts unreadable.
"Hey, little Nakime~" Doma said lightly. "This man might end up as your food later, you know? Not as good as a woman, but still worth eating~"
Nakime lifted her head slightly, then quickly lowered it again, plucking at the strings in uneven intervals.
"Come on, don't be so cold. If he hadn't already eaten two girls by the time you brought him here, he would've been my food," Doma said with a laugh. "You know—I'm quite picky about my meals."
"Y-yes… Thank you, Lord Doma."
"Oh, don't mention it~ By the way, would you like me to prepare him as an ice sashimi later?"
Nakime fell silent once more.
Mikazuki looked up at Doma. "Didn't you say Muzan wanted to see me?"
"Yes~"
"Then why hasn't he appeared yet?" Mikazuki glanced around the platform where Nakime sat. "Someone as insignificant as me should be an eyesore just for being alive, shouldn't I?"
"Oh dear, I wouldn't know~" Doma replied, gently waving his fan. "How could I possibly understand the Lord's thoughts?"
Mikazuki frowned slightly. Taking advantage of the moment he lowered his gaze, he looked at Nakime again, his hand tightening inside his sleeve. Just as he was about to speak, Nakime's voice rang out.
"The Lord has arrived."
At the same moment, the biwa rang sharply. A paper sliding door appeared out of thin air on an elevated platform. As it opened, a man dressed in a perfectly tailored black suit stepped out.
The instant Mikazuki saw him, an overwhelming sense of danger crashed over him, forcing his spine to stiffen as his body trembled uncontrollably.
Yet what made him tremble wasn't fear of the mind, but the instinct of a living being sensing absolute peril. Every instinct screamed that, before this seemingly refined and fragile man, resistance was impossible.
Mikazuki's expression darkened.
[What terrifying pressure… Is this the Demon King, Muzan Kibutsuji?]
Muzan didn't look at Mikazuki at all. From above, he gazed down at Doma.
"You said he's that boy's friend?"
"Mm~ Probably~" Doma tapped his chin with his folding fan.
"Even if he isn't, he definitely has some connection to Akiwa~"
"Where is the proof?"
"As for the evidence~ while I was investigating Akiwa on your orders, I learned that the Demon Slayer Corps' new prosthetic craftsman was introduced by Akiwa," Doma said lightly. He walked up to Mikazuki, used his folding fan to lift the haori sleeve on the side of his prosthetic, then gently tapped the wooden arm.
"This level of craftsmanship—so realistic—is rare these days~ He must have pulled some strings, right? And he figured out who Akiwa was not long after, which means they're quite familiar with each other~"
"Well done, Doma." A faint smile appeared on Muzan's handsome face as his arrogant gaze finally settled on Mikazuki. "I didn't expect such an unexpected gain."
Mikazuki looked up at Muzan and suddenly laughed.
"How unbelievable."
Muzan frowned slightly. "What's unbelievable?"
"I thought my life would end just like this," Mikazuki said, shaking his head with a smile. "I never imagined I'd actually see the Demon King with my own eyes… I'm so excited I'm trembling."
Doma narrowed his eyes, snapping his folding fan open to cover his face as he retreated several steps, deliberately clearing the space. He had no intention of being caught up in the fallout.
"Excited?" Muzan's plum-red vertical pupils fixed on Mikazuki as crimson, whip-like tendrils spread out behind him. "Every cell in your body reeks of fear… What shameless bravado."
"I'm already meat on the chopping block—there's no escape," Mikazuki Reima said, staring straight into Muzan's eyes. "Why not let me die knowing the truth? You're the Demon King. Surely you wouldn't bother deceiving a nobody you could crush at will, would you?"
"…Are you giving me orders?"
Feeling the killing intent radiating from Muzan, Mikazuki's breath hitched. He didn't answer. Instead, he asked his own question.
"On the way here, I heard this demon and another short demon say that one of our Hashira is a demon, and that you're targeting him. Is that true?"
Muzan didn't reply. An inexplicable smile tugged at the corner of his lips, and the killing intent around him eased slightly.
That reaction only darkened Mikazuki's expression further. "Then… were he and his brother both demons you transformed—ones who broke free of your control?"
"Kokushibo was indeed a demon I transformed," Muzan said coolly.
"But that irritating puppet was not."
He narrowed his eyes, a trace of ridicule curling at his mouth.
"Others I can ignore, but Ubuyashiki—after pestering me for a thousand years—should have been able to infer this much. After all, that puppet gave me plenty of trouble hundreds of years ago as well… What? He didn't tell you?"
[So the Master… knew?]
Mikazuki's pupils shrank. He instinctively recalled Hiru's interactions with Ubuyashiki Kagaya, his expression growing heavier by the second.
"Looks like you've realized it," Muzan said with a hint of amusement. "How laughable. The Demon Slayer Corps actually elevated a demon to Hashira."
"And his brother?" Mikazuki pressed.
Seeing Mikazuki's grave expression clearly pleased Muzan.
"Ah. That was hundreds of years ago, when Breathing Styles first appeared. I found them interesting, so I sought out a swordsman and transformed him… Unfortunately, even after all these centuries, Kokushibo still couldn't completely abandon those useless emotions. He wavered after a few words from that puppet… utterly disappointing."
[He still hasn't mentioned Yoriichi. Why? Isn't Yoriichi the demon he transformed?]
Questions surged through Mikazuki's mind.
[According to Muzan, Breathing Styles emerged hundreds of years ago. Hiru was a demon from that era, so Yoriichi—whom Hiru calls his brother—should also be a demon. That would explain their terrifying physical strength… but then why are neither of them affected by sunlight or wisteria?]
"I've satisfied your pitiful curiosity," Muzan said, looking down at Mikazuki.
"Now I'll give you a choice. First, you tell me everything you know about Sun Breathing, and then I kill you. Second, I turn you into a demon and read it directly from your mind."
Still lost in thought over Hiru and Yoriichi, Mikazuki froze. "…Sun Breathing?"
"Does the Demon Slayer Corps not even know about Sun Breathing anymore?" Muzan's voice grew sharp. "That breathing style was created by that man—and it caused me no small amount of trouble."
Mikazuki could clearly feel Muzan growing irritable again.
Yet beneath that agitation lurked a far deeper fear.
[Muzan is afraid? Afraid of what—Sun Breathing? If I remember correctly, Yoriichi said he used Sun Breathing…]
Mikazuki's pupils contracted sharply.
[Wait—could Yoriichi be the original swordsman from hundreds of years ago?!]
Seeing Mikazuki lapse into stunned silence after Sun Breathing was mentioned, Muzan's patience finally snapped.
The whip-like tendrils lashed out, flinging Mikazuki straight into the wall beside Nakime. His voice turned vicious.
"Answer me, trash. Do you have any idea who you're standing before?"
Mikazuki slid down the wall and spat out a mouthful of blood. He could feel every rib in his chest shatter from the blow, yet his mind was still reeling from the revelation he'd pieced together.
[I remember… once, when Yoriichi came to see Hiru, I asked why he wore a mask when his face had no scars. What did he say? What did he say…? Wasn't it—'It would be troublesome if I were recognized'? Recognized? By whom?]
Mikazuki Reima coughed violently, blood flooding his mouth and nose, but he still forced himself to look up at Muzan, memories racing through his mind.
[Muzan… It was Muzan! Yoriichi is the one who has terrified Muzan for centuries!]
"Looks like you've chosen the second option," Muzan said, walking down the stairs that appeared from thin air until he stood before the kneeling, coughing Mikazuki. The nail on his right index finger sharpened to a lethal point.
"Why do you never learn? You only need to submit to the strong."
[No. I can't let him know. I can't let Yoriichi's existence be exposed. I can't be turned into a demon!]
Mikazuki made his decision in an instant.
Using his collapsed posture, he swallowed the pouch of medicine he'd intended to use to ambush Muzan or Nakime. Even as it scraped painfully down his throat, he burst into uncontrollable laughter.
Watching Mikazuki laugh so suddenly, a vein throbbed at Muzan's temple. "…What are you laughing at?"
"Nothing," Mikazuki said as he forced himself upright, blood pouring from his eyes, ears, nose, and mouth.
"I just didn't expect I'd end up using it on myself."
Muzan's brow furrowed deeply.
"Muzan, haven't you ever wondered why the Demon Slayer Corps opposes you?"
Mikazuki continued.
"Now I'll tell you…"
Mikazuki felt a surge of blood rise in his throat, forced it back down, and glared at Muzan with a mix of madness and exhilaration.
"As long as you live, the Demon Slayer Corps will never fall. So, Muzan… I'll be waiting for you in hell."