Infinite Castle
"?!?!?!"
Nakime plucked the strings of her biwa. Three sharp tones echoed as she prepared to summon someone. But the moment her fingers pressed again—
Zheng!
The strings snapped violently, the recoil slicing straight through her left wrist.
"!?"
Nakime didn't flinch. Blood trickled down her hand, but with her right arm she gripped the instrument closer. Her eyes, hidden behind her long bangs, turned bloodshot.
"…The line I use to locate Lord Muzan… it's broken…" she whispered.
Before she could process it further, cold frost spread through the air, followed by a light, mocking voice.
"Oh my~ Nakime, did you bring me here just to watch a little wrist-slashing show?"
From the mist stepped Dōma, dressed in the ornate robes of the Eternal Paradise cult. He pressed his palms together as though applauding, eyes narrowed in feigned delight.
Nakime ignored him. Her severed hand regenerated quickly, and she plucked the broken string again—only for it to snap a second time.
Dōma's smile faltered for a moment, his eyes shifting elsewhere.
A shadow loomed above. Hanging upside-down from a moving wall was a muscular figure covered in jagged tattoos—Akaza. His piercing eyes burned with disgust as he noticed Dōma watching him. His fists clenched by instinct.
Thud!
Akaza dropped to the ground, landing in silence.
"Eh~ Akaza-dono is here too!" Dōma chirped, instantly flashing behind him, one hand sliding toward his shoulder like an old friend.
Shhk!
Akaza's fist ripped through Dōma's chest in a blur, then pulled back as he twisted away from the touch.
"…Don't bother me."
"Now, now~ We haven't met in decades, and you greet me like this?" Dōma chuckled, his body already knitting itself back together.
Before either could escalate, the air grew heavy. A suffocating pressure pressed down on the Infinite Castle, forcing even Dōma's grin to stiffen.
From the shifting walls emerged a towering figure with six eyes glowing like lanterns—Kokushibō.
"…Why have you called us here?" His voice was calm but edged with authority. "Has an Upper Moon fallen?"
Nakime steadied herself and bowed low. "Lord Muzan ordered me to summon the three of you. He said he had something to announce… but it seems he has encountered… difficulty."
The air grew colder. Kokushibō's six eyes bore into her, sharp enough to cut her apart.
"…Do you understand the weight of those words?" His aura crashed down like a storm.
Nakime trembled, her voice breaking under the pressure. But then, a message brushed through her mind—Muzan's direct command. She forced herself to speak:
"P-please, Master Kokushibō… Lord Muzan just informed me he is not in danger. Only… delayed."
"…You're certain?"
"I… I dare not lie."
Dōma clapped his hands lightly, stepping in to ease the tension. "There, there~ No need to frighten the poor girl. If she says Lord Muzan is safe, then he must be."
At last, Kokushibō withdrew his killing intent. Nakime let out a shaky breath of relief.
"…Since no further orders have come, I will return you to your posts now," she said carefully.
But Dōma tilted his head, waving. "Ah, Nakime Could you send me directly to Lord Muzan instead? It must be so lonely where he is"
"I… I cannot locate him at this time."
"Ehh~? That's a shame. I miss him so much—"
Shhhk!
Kokushibō's blade flashed, splitting Dōma neatly in two. Akaza, silent until now, smirked faintly as Dōma's body fell apart.
Sheathing his sword, Kokushibō spoke coldly. "Lord Muzan's affairs… do not concern you."
Dōma's pieces wriggled back together in seconds. He looked up with a childlike pout. "Oh my, Kokushibō-dono… why so harsh? Lord Muzan raised me too, you know~ His business is my business."
Slash—slash—slash!
In the next instant, Kokushibō reduced him to ribbons. Yet even as chunks of flesh writhed on the floor, Dōma's voice lilted on:
"Fufufu~ Could it be… that you're jealous?"
Kokushibō's eyes twitched faintly. Before his sword could strike again, Nakime intervened, teleporting Dōma away before the tension could explode further.
Eternal Paradise Sect
In an instant, Dōma reappeared within his own temple, seated comfortably on his ornate throne. His wounds stitched themselves back together without effort.
He tilted his head, giggling softly. "My, my… I never imagined Kokushibō-dono would react like that. How interesting~"
His gaze turned toward the corner, where an easel stood with a canvas. On it was the painted image of a gentle woman, her smile soft, her eyes warm.
Dōma rose, walked slowly toward it, and placed a hand over the painting. For once, his grin faltered. His brow knit slightly as he whispered:
"…Kotoha…"
The courtyard of a quiet mansion in the Tsugikuni estate.
The sun had long since set. Dark clouds swallowed the night sky, and a sharp, cold wind swept through the yard.
Without sunlight, I could finally move freely. I could go anywhere I wanted.
But… I couldn't leave this yard.
Two huge trees stood at opposite ends of the courtyard, their branches thick with leaves. I lay stretched across one of them, holding a medical book I'd borrowed from Kanae at the Butterfly House.
On a small fork in the branch beside me sat a plate piled with nuts and sweets. Every so often, I reached over, grabbed one, and popped it into my mouth.
It's not that I liked perching in trees—it's that I had no choice. The ground beneath was completely off-limits.
Because that space belonged to Tsugikuni Yoriichi's training ground.
Whoosh! Whoosh! Whoosh—!!
Yoriichi wasn't using Breathing Techniques. Instead, he relied purely on muscle and willpower, swinging his Nichirin blade with flawless precision.
Breathing strengthens the body, suppresses pain, and keeps a swordsman alive far beyond human limits. With it, an injury that should feel like 100% pain drops to barely 10 or 20%.
But the moment breathing stops, that pain comes roaring back. That's the price.
Most Hashira, and even ordinary Demon Slayers, practice breathing so constantly that they use it in their sleep.
But Yoriichi—the man who created Breathing—wasn't using it at all. He was forcing his body to train without it.
From above, I peeked through my book and watched him. Even without breathing, his speed rivaled a Hashira. Every strike carried a weight that made my chest tighten.
Why was he so obsessed with strengthening his body alone?
Maybe it's because… back in the Sengoku era, after Breathing was taught to the Corps, everyone relied on it too much. Their natural strength withered. Even Hashira of that era weren't much sturdier than ordinary men—they lived and died by technique alone.
That's why Kokushibo tore through them so easily. He mocked their weakness.
And that was the bloodiest generation in the history of the Corps.
I thought of the time Yoriichi trained Tanjiro. His methods focused first on raw strength, not breathing alone. Because of that, Tanjiro's base power far surpassed Zenitsu and Inosuke's.
Realizing this, a chill ran through me. I tugged my book up to cover my face and, against my will, pictured the muscle hidden beneath Yoriichi's robes.
"…Damn it. I've never actually seen under his haori… Is it really like that?"
As if sensing my stare, Yoriichi stopped mid-swing. His head tilted upward. His calm eyes locked onto mine.
Panic seized me. I shoved my face into the book, curling in on myself like a cat caught stealing food.
Yoriichi's lips curved faintly, and for just a moment, a small chuckle escaped him.
Creak—
The mansion doors swung open. Yoriichi turned to look. I cautiously lowered my book and peeked as well.
The one who strode inside was unmistakable—
Uzui Tengen, the Sound Hashira.
"Yo! Long time no see, Tsugikuni Yoriichi! As flamboyant as ever, I see!"
Uzui marched straight toward Yoriichi, all glittering confidence, without once glancing up to notice me.
"…Uzui. Is there something important?" Yoriichi asked calmly.
Uzui blinked, caught off guard by the directness. After clearing his throat a few times, he spoke.
"Three years now, strange disappearances… A demon's involved. My wives took the mission last week. But no word has come back since. Judging from their last letter, the target's at least Lower Rank… maybe Upper."
Yoriichi's voice cut in, quiet and sharp. "The point."
Uzui's showy grin slipped for a moment. Then he spoke in one breath:
"I can handle the demon myself—but I don't know if I can save the civilians caught in the middle."
Ah. So that was it. He wanted backup. But judging from his eyes, what he really feared for was his wives.
"So… you want me to assist you?" Yoriichi asked.
"That's right! Flashy answer! You've got free time, and no one's more reliable than you."
Yoriichi nodded. "Very well. But I'll bring someone else." His gaze flicked upward—to me.
Only then did Uzui notice I was there. Up until now, I'd been completely ignored.
Great. The future Demon King, treated like thin air. How insulting.
I snapped my book closed, narrowed my eyes, and called down with mock sweetness:
"Hey Long time no see, Mr. Groundhog"