A few days earlier…
Hiru had originally thought that, at worst, he might run into Muzan sometime before next spring and get beaten down again.
If things went even worse, perhaps he would be devoured outright, only for his brother to come knocking afterward and put an end to everything.
What he never expected was to receive news that Mikazuki had gone missing on the road to Mount Fujikasane.
"Missing?" Hiru looked at the Kakushi who had come to report. "That Mikazuki?"
"Yes. Lord Mikazuki had been resting at the Wisteria House. After saying he was heading to Mount Fujikasane to test some medicine, he never returned. At first, we assumed he had been urgently recalled, so a comrade brought Lord Mikazuki's medicine chest back to headquarters."
"However, even after reaching headquarters, the Kakushi were unable to locate Lord Mikazuki."
The Kakushi looked uneasy.
"Further investigation revealed that Lord Mikazuki lost contact somewhere between the Wisteria House and Mount Fujikasane… The Oyakata-sama and the Hashira have already been informed…"
"..."
"...How long has he been missing?"
"It's difficult to determine the exact time. If we count from when Lord Mikazuki departed for Mount Fujikasane, it should be five days now."
"Five days…" Hiru silently clenched the paintbrush in his hand. "...I understand."
"...Yes. I'll take my leave."
The Kakushi bowed and withdrew.
"Please take care."
Hiru set down the brush, now cracked from the force of his grip, stood up, and opened the window. Sunlight streamed in as he let out a long breath.
"For something like this to happen…"
Crack.
Hiru lowered his gaze to the window sill, which he had unknowingly gouged with his fingers. At last, a shadow crept over his usually gentle expression.
"What on earth is going on…"
...
Five days earlier, near Mount Fujikasane, at the Wisteria House.
"Lord Mikazuki, are you certain you don't need us to accompany you?"
"Ah, I was a Hashira once, after all. There's no need to worry. Besides, there aren't any powerful demons around Mount Fujikasane. I'll be back in at most two days." Mikazuki Reima slid his Nichirin Blade back into its sheath, lifted his head to the cool moonlight, and smiled. "It's been a long time since I went out at night. I almost miss it…"
"Yes… May your martial fortune be prosperous."
"Ah, thank you."
After checking his equipment one last time, Mikazuki left the Wisteria House and set off toward Mount Fujikasane. Along the way, he gazed at the softly lit night, feeling a touch of nostalgia.
Back when he was still actively slaying demons, nights were illuminated by little more than a handful of bean-sized, flickering lanterns.
Whether one could see the road at all depended entirely on how bright the moon was that evening.
"Electricity really is convenient…"
Mikazuki was musing over the changes of the times when he passed an alley and suddenly frowned, his hand instinctively resting on the hilt of his sword.
"...A roaming demon?"
But once he stepped into the alley and clearly saw what lay ahead, a look of disgust crossed his face.
Floating in midair was a single eyeball. Sensing Mikazuki's approach, it slowly rotated, fixing its pupil squarely on him.
[A reconnaissance-type Blood Demon Art… It's already reached the vicinity of the Wisteria House. I'll have to remind the Kakushi later to stay on guard.]
Mikazuki frowned and reflexively tried to draw his blade to split the eye apart. Yet no matter how he pulled, the sword would not move even an inch.
He glanced down and saw that a thick layer of ice had formed where the scabbard met the guard. It was this ice that had sealed his blade in place.
Mikazuki's pupils shrank instantly. He tried to call out a warning, but a blast of frigid air rushed at him, coating the lower half of his face in a thin layer of frost.
"Honestly… I was wondering why I was suddenly summoned away from my busy work."
A voice sounded behind him, light and casual. "So Little Nakime was discovered after all."
Mikazuki whirled around, only to find that the demon with white oak–colored hair had appeared behind him at some point. The demon leisurely waved a golden folding fan.
What truly filled Mikazuki with dread, however, were those eyes—eyes that seemed to hold seven-colored rainbow light within them.
[Upper Moon… One? Why would an Upper Moon be here? I remember… his name should be Doma. An ice-using demon… This is bad.]
"Hm… I can't let you report what's happening here to the Demon Slayer Corps."
Doma tapped his chin with the fan, looking troubled.
"If Akiwa finds out, things will get really troublesome for me. What should I do? I just ate, so I really don't feel like eating right now."
Even knowing his chances of survival were slim, Mikazuki did not panic.
He raised a hand and tapped at the ice crusting his face. After confirming it wouldn't break, he made no reckless move, only frowned at Doma.
"Oh my, you're so calm. That part of you really resembles Akiwa."
Doma smiled.
"Perfect timing—I could use a break myself. Let's have a little chat. Just don't shout to alert anyone else, okay? Otherwise, I'll have no choice but to destroy this entire area."
Mikazuki felt the ice on his face begin to melt and carefully worked his stiff jaw.
"You've been mentioning Akiwa over and over since earlier… Are you talking about someone from our Demon Slayer Corps?"
"Ah, yes. Someone from your Demon Slayer Corps. Little Akiwa is really amazing~"
Doma chuckled.
"The last time, I got beaten up pretty badly by her."
[Last time… wasn't that Hiru's doing? Wait—Hiru… Akiwa… That can't just be a coincidence.]
Mikazuki felt as though he had stumbled upon something unbelievable.
"Little Akiwa is so adorable, and she even said she really likes me~ I was absolutely thrilled~"
Doma clasped his hands behind his back, a bewitching smile spreading across his face. "But is that all you wanted to say? I thought you'd ask something more interesting."
"Hah… You make it sound like you'd answer even if I did."
Doma snapped his folding fan open, his seven-colored eyes locking onto Mikazuki, his voice still light and amused.
"Why wouldn't I? You're not going back anyway. If that's the case, at least you can die feeling happy. I'm really quite kind, you know~"
"Then you—"
Before Mikazuki could finish, an ornate paper sliding door materialized beside him out of thin air. A male voice, edged with irritation, came from within.
"You idiot. Stop wasting time and finish him already."
"Oh dear, Akaza-sama is just as dull as ever~"
Doma waved his fan.
"But this man is top-quality food~ It would be such a waste to kill him and throw him away. Why don't you eat him instead, Akaza-sama?"
The ornate door slid open at last. A demon with peach-pink hair glared up at Doma, veins bulging at his temples.
"I don't have time for your nonsense. If my battle hadn't caused such a commotion, do you really think it would've been your turn to show up?"
At the side, Mikazuki's pupils contracted sharply.
[Another Upper Moon? What are they plotting? Why are they all gathered here?]
Tears welled up in Doma's multicolored eyes.
"Oh, Akaza-sama, we're supposed to be best friends, aren't we? Don't be so hard on me~ I'll be hurt, really hurt, you know? Look, I'm even crying~"
Akaza clicked his tongue and frowned at Mikazuki. His gaze landed on Mikazuki's wooden prosthetic, the impatience in his eyes growing stronger.
"Whatever. Just deal with him quickly. Don't linger outside for too long. If you don't want to eat him, hand him over to Nakime. We can't afford to let that guy notice."
"Ah, you're right. Leaving a corpse behind would be terrible if Akiwa found it~"
Doma tilted his head toward Mikazuki and smiled once more.
"Mm, let's do it that way. After all, Little Nakime needs power to grow too."