Chapter 25

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独占  

Dokusen 

Morning came not with the shrill, demanding caw of a crow, but with the soft, golden slant of sunlight creeping across the tatami mats.

You woke up slowly, the heavy fog of exhaustion lifting layer by layer.

For a brief, disorienting second, you didn’t recognize the ceiling.

It wasn’t the plain plaster of your usual quarters, but elegant cedar grain. Then, the scent hit you—a soothing blend of chamomile, old paper, and wisteria.

And then, you felt the weight draped across your chest.

You shifted your gaze downward. Shinobu was still fast asleep, her head resting comfortably in the crook of your neck, her dark hair a beautiful spill of silk across your shoulder. One of her arms was thrown carelessly across your waist, holding you in place with a surprisingly strong grip, and one of her bare legs was tangled intimately with yours.

You held your breath, utterly terrified that the slightest movement would wake her or, worse, break the fragile reality you had somehow stumbled into.

She… reciprocated. The memory of last night hit you like a physical wave, flushing your cheeks with sudden, intense heat.

The confession, the tears, the desperate grip of her hands, the kiss—

God, the kiss.

“Your heart is beating incredibly fast,” a soft, raspy voice murmured against your collarbone.

You jumped slightly. Shinobu didn’t lift her head, but you felt her lips curve into a smirk against your skin.

“I— I thought you were asleep,” you stammered, your voice thick with morning grit, your pulse accelerating even more as her fingers lightly traced the edge of your ribs.

“I was. Until my pillow started vibrating like a trapped hummingbird.” She finally shifted, propping her chin on your chest and looking up at you through half-lidded, sleep-softened violet eyes. The early light caught the messy strands of her hair, making her look entirely undone and beautiful.

Fuck, she’s so pretty.

“Good morning,” you managed to whisper, reaching up instinctively to brush a stray lock of hair behind her ear, letting your fingertips linger against the warm skin of her cheek.

She leaned into the touch, her eyes fluttering shut for a brief moment as a soft hum vibrated in her throat. “Good morning.”

For the first time since you had arrived at the Butterfly Estate, there was no looming threat of a mission, no frantic lab experiments demanding immediate attention.

Just the quiet hum of the waking estate and the steady, intoxicating warmth of the woman in your arms.

“I could get used to this,” you murmured, tracing the line of her shoulder over the soft cotton of her yukata.

“You had better,” Shinobu replied. She shifted her weight, sliding up just enough to press a slow, affectionate kiss to the corner of your mouth. Her tone was light but laced with that new possessive edge she had laid claim to last night. “I don’t intend to let you sleep anywhere else.”

Your heart did that frantic little stutter again. You buried your face in your hands, groaning softly through your fingers as your face burned. “You can’t just say things like that with a straight face, Shinobu. My poor heart can’t take it.”

She laughed, the sound bright and genuine, filling the small room as she gently pried your hands away to kiss you properly.

· · ─────── · 𓅪 · ─────── · ·

Reality, unfortunately, could only be kept at bay for so long.

By the time you both emerged from her room—carefully staggering your exits by five minutes to maintain at least a semblance of professional decorum, though the incredibly knowing look Aoi shot you in the hallway suggested your efforts were entirely futile—the Butterfly Estate was already bustling.

The surgical wards were full. The fallout from Yoshiwara was severe, and the air was thick with the smell of medicinal herbs, fresh linens, and the lingering tension of recovery.

You slipped easily back into your role, tying back your hair and donning a fresh samue. You carried a tray of fresh bandages, water, and pain medications into Ward Two, where the Kamaboko squad was housed.

“Ah! ______-saaaaaan!” Zenitsu wailed the moment you stepped through the shoji screen. He was sitting up in his bed, his good arm waving frantically. “It hurts! Everything hurts! Aoi-chan is being so mean to me, she tied the bandages too tight, I’m going to lose circulation and die!”

“You are not going to die, Zenitsu,” you sighed, walking over to check his vitals. “Aoi tied them tightly so you wouldn’t pull your stitches when you thrash around in your sleep.”

“I don’t thrash!”

“You fell out of bed twice last night, Monitsu,” Inosuke grunted from the neighboring bed, his boar mask resting on the table beside him. His chest was heavily wrapped, but he was currently attempting to do sit-ups, much to the absolute horror of his healing ribs.

“Inosuke, lay flat before I call Aoi,” you threatened, pointing a pair of forceps at him.

He immediately dropped back onto the mattress with a heavy thud, grumbling about how the “Great Lord of the Mountains doesn’t need to listen to underlings.”

You shook your head and moved to the center bed. Tanjiro was awake, propped up slightly on his pillows. He looked incredibly pale, the dark bruises under his eyes stark against his skin, and the chest tube Shinobu had inserted yesterday was still doing its vital work. But his burgundy eyes were bright and incredibly warm.

“Good morning, ______-san,” he rasped, offering a weak smile. “Thank you for taking care of us.”

“Don’t thank me yet. You still have to drink the wisteria medicine, and it tastes awful,” you joked gently, setting a small cup on his bedside table.

As you leaned in to adjust his pillows, Tanjiro’s nose twitched. He blinked, tilting his head slightly, his gaze focusing intensely on you.

“Is something wrong, Tanjiro?” you asked, freezing in place. “Does your chest hurt?”

“No, it’s not that,” he murmured, his brow furrowing in confusion. “You just… you smell different today, ______-san.”

You felt the blood drain from your face.

Oh no.

“Different?” you echoed weakly.

“Yeah.” Tanjiro offered you a purely innocent, incredibly bright smile. “Your scent is usually very calming, like fresh paper and rain. But today… you smell exactly like Shinobu-sama. Like, a lot. It’s completely masking your own scent. And you smell incredibly happy!”

Zenitsu’s crying instantly stopped. His golden eyes snapped toward you, wide and calculating. Even Inosuke stopped grumbling, turning his head to stare.

“I— well, I was working in the lab,” you lied frantically, your face burning so hot you were sure you were glowing in the dark. “Very closely. With the wisteria. That’s all.”

Tanjiro tilted his head, clearly entirely oblivious to your gay panic. “But it’s not just wisteria. It smells like her personal—”

“Okay, time for your medicine!” you exclaimed, shoving the bitter cup toward his mouth.

“Mmph— ______-san!”

· · ─────── · 𓅪 · ─────── · ·

You practically fled Ward Two, deciding your services were much better utilized in Ward One, where Tengen was recovering.

Surely, the Sound Hashira would be less observant than a boy with a superhuman nose.

You were dead wrong.

When you slid the door open, the room was a chaotic blur of noise and color. Tengen was sitting up against the pristine white pillows of his bed. His stump was heavily bandaged, and he looked incredibly annoyed as his three wives fussed over him like frantic mother hens.

“Uzui-sama, you need to eat the porridge!” Suma was whining, holding a wooden spoon aggressively near his face.

“I told you, I don’t want the flamboyant mush! Bring me something with actual flavor!”

“Stop being a baby and eat it,” Makio snapped, smacking the back of his uninjured shoulder.

Hinatsuru just sighed gracefully from her spot at the foot of the bed.

“Excuse me,” you interrupted softly, stepping into the room with a fresh tray of medicinal pastes. “I need to check the dressing on your arm, Uzui-san.”

“Ah! The very capable assistant!” Tengen boomed, his remaining eye lighting up. “Come in, come in. Save me from these three.”

You stepped up beside his bed, carefully unwrapping the outer layers of his bandages to check for any sign of infection around the surgical site Shinobu had worked so hard to close. Your movements were quick, steady, and practiced.

“You know,” Tengen mused, leaning his head back against the wall as he watched you work. “You’ve got remarkably steady hands. You didn’t even flinch when I was bleeding all over the courtyard yesterday.”

“I’ve had a lot of practice cleaning up messes,” you replied dryly, applying the green-tinged paste to the edges of the wound.

“She’s so gentle, too,” Suma sniffled, wiping away a stray tear as she watched you. “She doesn’t yell like Aoi-chan does.”

“She has a good head on her shoulders,” Makio agreed, crossing her arms and looking you up and down approvingly. “And she’s pretty.”

You blinked, feeling the tips of your ears burn. “Um… Thank you?”

“I’ve been thinking,” Tengen said loudly, ignoring your discomfort entirely. A flashy, arrogant grin spread across his bruised face. “Since I’m retiring from the front lines, I’m going to need a highly capable medic on hand. Someone to keep me in peak flamboyant condition.”

He leaned in closer, his crimson eye sparkling with mischief.

“What do you say, ______? Care to be wife number four?”

You dropped the roll of bandages.

It hit the wooden floorboards with a soft thud and rolled away. Your brain completely short-circuited. Your mouth opened, but no sound came out.

“Huh— What?” you finally choked out, your voice cracking an octave higher than normal. “Wife number four? I— Uzui-san, I am flattered, but I am absolutely not—”

“Oh, yes!” Suma clapped her hands together delightedly, bouncing on her heels. “Please! It would be so fun! We could do your hair!”

“I wouldn’t be opposed,” Makio shrugged. “You seem like you can handle yourself in a fight.”

Hinatsuru smiled warmly at you. “We would take very good care of you.”

“See? The wives are on board,” Tengen declared triumphantly, pointing a bandaged finger at you. “It’s a very flamboyant offer. You’d never be alone for anything, and—”

“I am going to have to stop you right there, Uzui-san.”

The temperature in the room plummeted so fast you could almost see your breath turning to frost in the air.

Tengen froze. Suma squeaked in sheer terror and hid behind Makio.

You turned your head slowly, your heart migrating into your throat.

Shinobu was standing in the open doorway. Her posture was perfectly relaxed, her hands tucked neatly into the wide sleeves of her haori, and her signature, serene smile was plastered across her face.

It was the most terrifying thing you had ever seen.

A thick, pitch-black aura of murderous malice seemed to radiate from her, practically suffocating the air in the room. A prominent, throbbing vein was visible on her pale temple.

Oooh no.

“Kocho,” Tengen greeted, his voice losing just a fraction of its usual bravado as he eyed her warily.

Shinobu glided into the room. She didn’t walk; she floated, silent as a ghost, her footsteps making absolutely zero sound until she was standing directly behind you.

“My, my,” she said, her voice dripping with enough artificial sweetness to give someone a cavity. “I step away to review Kanao’s medical charts for a mere ten minutes, and I return to find you attempting to poach my most vital assistant from right under my nose. How incredibly… unwise of you.”

“I was merely making a generous offer,” Tengen defended himself, though he notably leaned back against his pillows, putting more distance between himself and the Insect Hashira. “She’s a beautiful, highly capable woman. She’d make an excellent fourth wife.”

Shinobu’s smile didn’t waver, but her violet eyes went completely, terrifyingly dead.

Slowly, deliberately, she lowered one hand from her sleeve. She didn’t just place it on your shoulder; her hand slid down to wrap firmly around your waist, pulling your back flush against her in a possessive, unyielding grip. Her other hand came down to rest on your bicep, her fingers curling against the muscle.

You swallowed hard, your face turning a brilliant shade of scarlet as your gay panic reached critical mass.

Oh my god.

She is marking her territory.

I am her territory. I don’t know if I find that hot or scary.

“I must decline your highly inappropriate offer on her behalf,” Shinobu said smoothly, her thumb stroking your bicep in a movement so fiercely intimate that Makio’s eyebrows shot straight up into her hairline.

“Is that so?” Tengen asked. His eye narrowed slightly as he observed the placement of her hands, the tension radiating from her, and the way you were melting into her touch. A slow knowing grin began to replace his apprehension. “And why is that?”

“Because,” Shinobu replied, her voice dropping an octave. She lost the sweet facade entirely, her tone settling into something else. “She is already taken.”

Silence descended on the ward.

Suma gasped dramatically, her hands flying to her cheeks. Hinatsuru hid a small, knowing smile behind her hand.

“Taken? Oh, really…” Tengen chuckled, leaning back, clearly enjoying this new development. “By who?”

Shinobu’s closed-eyed smile returned, but the malice had transformed into pure, unadulterated smugness.

“By me.”

The room went completely silent once again.

You were certain you were going to spontaneously combust right there by the bed.

Shinobuuu!

“Hahahaha, I see!” Tengen threw his head back and let out a booming laugh that rattled the medical trays. “Well! You should have just said so, Kocho. I absolutely respect a flamboyant territorial claim!” He winked directly at you. “You’ve got your hands full, kid.”

You dared not say anything and buried your burning face in your hands.

“Now, if you are quite finished harassing her,” Shinobu said smoothly, her grip on your waist tightening just enough to make you shiver. “I believe Aoi has a particularly vile-tasting herbal remedy she needs you to drink. Good day, Uzui-san.”

Without another word, Shinobu grabbed your wrist and hauled you away from the bed, practically dragging you out of the ward before you could even squeak out a goodbye.

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She didn’t stop walking until she had pulled you into the empty, sunlit supply closet at the end of the hall, sliding the heavy wooden door shut behind you with a sharp clack.

You were pressed back against the wooden shelves, surrounded by the smell of starched linen and dried lavender.

Shinobu stood in front of you, her chest heaving slightly, her face flushed with a mixture of residual anger and something entirely different.

“A fourth wife,” she muttered, glaring at the space next to your head, her hands balling into fists. “The absolute, unrelenting nerve of that man.”

“Shinobu,” you tried, fighting the massive, stupid grin that was currently fighting its way onto your face.

“He already has three! Why on earth would he need a fourth? And of all people, he decides to proposition—”

“Shinobu.”

You reached out, catching her hands and pulling her a half-step closer until she had to look up at you. Her violet eyes were blazing.

“Are you jealous?” you teased softly, rubbing your thumbs over her knuckles.

“I am not jealous,” she retorted immediately, though the dark flush on her cheeks betrayed her completely. “I am merely protective.”

“Protective.”

“Yes. You are vital to the laboratory.”

“So that intense territorial display in there, telling the Sound Hashira, in front of his three wives, that I was taken by you and all… That was just standard employee retention?”

She narrowed her eyes at you, clearly annoyed that you were finding this so amusing. But then her gaze dropped to your lips.

The spark of irritation ignited into something far more visceral.

She stepped completely into your space, crowding you hard against the shelves. Her hands slipped free of yours, one shooting up to tangle fiercely in the hair at the nape of your neck, the other pressing flat against the chest of your samue to shove you back against the wood.

You grinned like a damn fox.

Woopsie.

“Do you have any idea,” she whispered fiercely, her voice dropping to a silken, breathless register that sent a jolt straight to your core, “how infuriating it is to hear someone else try to claim you?”

“I was never going to say yes,” you breathed, your own hands flying to her waist, gripping the fabric of her uniform tightly. You felt her breath hitch when you did so.

“I know,” she murmured, her thumb tracing the line of your jaw, her gaze dropping to your mouth. “But I wanted to remind you anyway. You don’t realize how captivating you are, do you?”

“Wha— Captivating? Me?” you choked out, your heart hammering against your ribs.

“Yes, you,” she confirmed. “You are mine, and I do not share.”

“Hahaha, good,” you chuckled softly as you managed to whisper, leaning down to meet her. “Because I only want to be yours.”

The confession was swallowed by her lips.

It was a collision. Deep, searing, and possessive, fueled by the lingering fire that Tengen’s ridiculous offer had sparked.

Her mouth was demanding, parting yours with an urgency that sent a shockwave of heat through your veins. Her fingers tightened in your hair, tilting your head to angle the kiss perfectly, pulling a soft, helpless gasp from your throat.

“______…” She sighed your name against your lips.

You responded in kind, your arms wrapping securely around her waist to lift her flush against you, backing her further against the shelves until she was caged between you and the wood. The kiss was hot, heavy, and delightfully messy, erasing the sterile chaos of the morning wards and leaving only the certainty of her claim on you.

Her tongue swept past your lips in a way that made your head spin.

“Shinobu,” you broke away with a gasp, resting your forehead against hers, your chests heaving in unison. “You can’t— you can’t just ambush me in closets like this.”

“I am the master of this estate,” she murmured back, her lips brushing against yours with every word. “I can ambush you wherever I please.”

She leaned in to capture your lips again, her hand sliding down your back to pull your hips flush against hers. A soft whine built in your throat as the kiss slowed, turning from frantic and possessive into something achingly tender and deep.

You surrendered entirely, letting her set the pace, your thumbs stroking the sides of her waist as you lost yourself in the intoxicating reality of her touch.

The kiss lingered, desperate and heady, until a sudden, sharp caw! echoed from the courtyard outside the small frosted window.

Shinobu froze, pulling back slowly. Her lips were swollen, her violet eyes dark and hazy, but her Hashira instincts had already snapped back into place.

“A crow,” she whispered, smoothing the front of your samue with trembling fingers, struggling to catch her breath.

You nodded, resting your forehead against hers, your heart pounding a frantic rhythm. “Duty calls.”

· · ─────── · 𓅪 · ─────── · ·

The summons was abrupt, and the air of the Ubuyashiki Estate was electric with a tension entirely unlike the quiet reverence you had experienced during your private audience weeks ago.

Kagaya Ubuyashiki had called an emergency Hashira meeting. The events of the past twenty-four hours were a monumental, paradigm-altering shift in the tide of the war.

You had remained at the Butterfly Estate, pacing the laboratory floors, while Shinobu attended the meeting.

In the pristine courtyard of the Ubuyashiki Estate, the Hashira knelt on the white gravel in perfect, disciplined formation.

The atmosphere was charged with disbelief, confusion, and a frantic, hungry energy. Tengen and Kyojuro were noticeably absent, both recovering in the very wards Shinobu had just departed from.

The sliding shoji doors opened softly. Amane and two of her daughters guided Kagaya out onto the sunlit engawa.

Instantly, every Hashira lowered their head, bowing deeply until their foreheads nearly grazed the stones.

“Oyakata-sama,” Sanemi spoke first. His voice was stripped of its usual volatility, replaced by unwavering respect. “We pray for your continued health and happiness.”

“Thank you, Sanemi,” Kagaya replied softly. A gentle smile graced the unmarred half of his face. His sightless eyes gazed out over the courtyard, filled with an infinite, paternal warmth. “My beloved children. I have called you here today because the tides of our long war have finally begun to turn.”

A collective breath hitched among the gathered swordsmen.

“For the first time in over a hundred years,” Kagaya continued, his voice carrying effortlessly on the wind, “an Upper Rank has been slain.”

The courtyard erupted into a stunned, momentary silence before a wave of visceral shock washed over the Hashira. Sanemi’s head snapped up, a fierce, bloodthirsty grin breaking across his scarred face. Mitsuri gasped, covering her mouth with both hands, tears of joy springing to her eyes.

“Tengen Uzui, fighting alongside young Tanjiro Kamado, Zenitsu Agatsuma, and Inosuke Hashibira, successfully defeated Upper Rank Six in the Yoshiwara Entertainment District,” Kagaya announced, his smile deepening. “Tengen has sustained heavy injuries and has officially retired from the front lines, but he and his wives are alive and recovering at the Butterfly Estate.”

“A… flamboyant victory,” Obanai murmured, shaking his head in disbelief, though a rare note of profound respect colored his tone. “To think that flashy fool actually pulled it off.”

“Namu Amida Butsu,” Gyomei wept openly, pressing his large hands together. “The heavens have blessed us. The demons’ hold is fracturing.”

“It is a magnificent victory,” Kagaya agreed softly. “But that is not the only miracle the dawn brought us.”

The Hashiras instantly quieted, hanging on his every word.

“Kyojuro was dispatched to the Mugen Train, as you all recalled,” Kagaya stated. “There, he survived a direct, physical encounter with Upper Rank Three. The demon retreated before the sun. He lives.”

If the news of Upper Rank Six’s defeat was a spark, this was a lightning strike.

“Oyakata-sama, forgive my intrusion,” Obanai spoke up immediately, his mismatched eyes wide as he kept his head bowed. “The official field reports stated he survived because the demon’s regeneration was fundamentally compromised in the middle of the battle. By poison. Is this true?”

“It is,” Kagaya answered gently.

Sanemi turned his intense gaze sharply toward the Insect Pillar. “Oyakata-sama! Are you telling us that Kocho has developed a poison that halts an Upper Rank’s regeneration? That’s scientifically impossible. They burn through wisteria toxins in a matter of seconds! It’s a biological fact we’ve known for centuries.”

“Usually, yes,” Shinobu spoke up calmly. She remained kneeling, her posture perfect, turning her head slightly to address her peers. “But this was not a standard neurotoxin. It was a targeted compound. A catalyst, as we learned to call it.”

The surrounding Hashiras shifted, their intense gazes boring into her.

“Explain,” Sanemi demanded, his hand twitching.

“The compound is designed to bind specifically to the regenerative properties of demonic tissue,” Shinobu explained, her voice steady and perfectly clinical. “Rather than simply attacking their biology, it uses their healing against them. When Upper Rank Three attempted to rapidly reconstruct his damaged cells, the catalyst engaged with his cells, turning his own strength into localized necrosis. The harder he tried to heal, the more his cells tore themselves apart.”

Gyomei pressed his hands tighter together. “To manipulate the very curse of their immortality… What a terrifying, blessed weapon.”

“Wait, wait!” Mitsuri gasped softly, her eyes wide with awe. “Shinobu-chan, you made this? This is incredible! We can really fight them now! We have a real chance!”

Giyu looked up, his stoic face betraying a rare flicker of shock. “How did you synthesize such a thing in such a short time span, Kocho? That kind of thing defies anything in our current medical records.”

“I… did not do it alone,” Shinobu answered, her voice even, though a swell of fierce, protective pride expanded in her chest.

“Shinobu has been aided,” Kagaya interjected gently, drawing the attention of the courtyard back to the engawa. “By a gentle soul currently residing within the Butterfly Mansion. A sanctuary of knowledge. Thanks to their combined efforts, this catalyst was born.”

“Then we need this poison, and this person, immediately,” Sanemi demanded, leaning forward eagerly, his eyes burning with the desperate need to end the war. “Oyakata-sama, with all due respect, if there is a mind capable of this, we need them out here! We need them to train our medics, to mass-produce this. Bring this outsider before us so we can utilize their knowledge for the Corps, Oyakata-sama!”

Shinobu’s jaw tightened.

Her violet eyes flashed dangerously, her protective instincts flaring hot and fast, but she remained silent, deferring to the Master.

“No, Sanemi,” Kagaya said. His voice remained incredibly soft, devoid of any anger or reprimand, but laced with an unyielding iron that brokered no argument.

Sanemi blinked, stunned by the direct refusal. “Oyakata-sama?”

“And what do you suppose Muzan Kibutsuji will do, Sanemi,” Kagaya asked gently, “the exact moment he learns we have a human capable of unraveling his blood?”

Sanemi faltered, his mouth opening and closing.

“He will not rest until they are dead,” Kagaya continued, empathy radiating from his blind eyes. “He will send the Upper Ranks to tear through our defenses just to reach them. This child… is a fragile spark. To deploy them… to deploy her to the field, or to expose her identity broadly, is to invite the darkness to snuff her out. Her mind is her weapon, and it is a sanctuary we cannot afford to lose.”

“I understand the risk, Oyakata-sama,” Obanai narrowed his eyes, his tone cautious. “But surely the Hashiras—”

“Even among the Hashiras, secrets must be kept to minimize the risk of a leak,” Kagaya interrupted, his tone gentle but leaving absolutely no room for debate. “She will remain classified. She will not be deployed to the field, not yet. She will remain protected at the Butterfly Estate, under Shinobu’s direct jurisdiction.”

A heavy, solemn silence fell over the Hashiras.

“However,” Kagaya added, a warm smile gracing his lips as he sensed the tense frustration in the courtyard, “she is a member of our family now. Should your paths cross while visiting the Butterfly Estate to visit your recovering friends, you may extend your greetings. Get to know her. Treat her with the utmost respect, for she has given us the key to our victory. But her existence as the architect of this catalyst must never leave the lips of anyone present.”

The Hashiras lowered their heads in perfect, synchronized unison. If Kagaya deemed the asset too valuable to risk, but allowed her to be welcomed as family, it was absolute law.

“As you wish, Oyakata-sama,” Sanemi murmured respectfully, accepting the boundary.

“We will not deploy this compound recklessly,” Kagaya instructed his children. “Muzan must not know we possess a finalized means to hijack his creations’ regeneration until it is too late for him to adapt. It will be reserved for guaranteed, fatal strikes. But let it be known, my children… A spark has caught in the dark. The tide is turning.”

As the meeting concluded and the Hashira dispersed in a flurry of hushed, intense whispers, Shinobu stood up. She adjusted her butterfly haori, a quiet sense of pride blooming in her chest.

A member of our family now. The Master’s words echoed in her mind.

He had officially solidified your place within their ranks, effectively shielding your brilliant mind from the bloodlust of the front lines while demanding the absolute respect of her peers. The other Hashiras would not hunt for your secrets. They would not try to use you.

You were safe.

And, as her thoughts drifted back to the flushed warmth of your skin and the breathless way you had kissed her back in the cramped supply closet just hours ago, a deeply satisfied smile graced her lips.

You were safe, you were brilliant, and you were entirely hers.

She couldn’t wait to get home to you.

· · ─────── · 𓅪 · ─────── · ·

Miles away, hidden in a dimension of shifting gravity and impossible, Escher-like architecture, the air was suffocatingly cold.

The Infinity Castle ground its massive wooden gears. The singular twang of a biwa echoed through the sprawling, inverted halls as Nakime sat motionless on her platform.

In the center of the vast, shifting expanse, Akaza knelt.

The Upper Rank Three was missing half of his right arm. It was regenerating, but agonizingly slowly, the flesh bubbling and smoking with a strange, sickly violet hue. His body was trembling, not from cold, but from sheer terror.

He did not look up. He kept his forehead pressed to the wooden floor.

The overwhelming, crushing pressure of Muzan Kibutsuji’s presence filled the room, pressing down on Akaza’s shoulders until the wood beneath him literally splintered.

“You failed,” Muzan’s voice was a soft, deadly hiss. He stood before Akaza, his red eyes glowing in the dim light. “You encountered a Hashira. A simple, human Hashira. And you failed to kill him. You let the sun rise, and you ran.”

“Master,” Akaza choked out, blood spilling from his lips. “I beg your forgiveness. It was not… I would have killed him. I had my fist aimed at his solar plexus. But—”

“But what, Akaza?” Muzan’s voice turned incredibly sharp, resonating with a terrifying fury. “What possible excuse do you have for this pathetic display?”

“It was poison, Master,” Akaza gasped, clutching his smoking arm, his eyes wide with remembered panic. “He splashed me with something at the last second. It did not burn like standard wisteria. It… it targeted my regeneration. Every time I tried to heal, the poison multiplied. It locked my muscles. It forced my own cells to tear themselves apart. I had to choose between healing and fighting.”

Muzan went completely still.

The shifting rooms of the Infinity Castle seemed to freeze in place, the ambient noise dying instantly.

Muzan stepped forward, grabbing Akaza by the throat and lifting him effortlessly into the air. His crimson, slitted pupils narrowed as he analyzed the violet, smoking flesh of Akaza’s regenerating arm.

He could feel it. The lingering trace of the compound in Akaza’s blood.

It was brilliant.

It was terrifyingly specific.

It was something no human should have been able to calculate, let alone synthesize. It wasn’t just a toxin; it was a biological countermeasure designed to kill him.

To kill Muzan.

“A poison that hijacks the demonic cellular structure,” Muzan whispered, his eyes widening slightly as true, unfiltered rage sparked in his veins.

He dropped Akaza, letting the demon crash back to the floor with a sickening crunch.

Muzan turned his back, his mind racing through centuries of data. The Insect Pillar was known for her poisons, yes, but this was entirely beyond her usual scope.

This required a fundamental understanding of biology that simply did not exist in this era, much to his centuries of knowledge inconvenience.

Someone, somewhere in the Demon Slayer Corps, possessed knowledge that threatened the very foundation of his immortality.

His jaw tightened, a rare flicker of genuine frustration breaking his composed facade.

First, the boy with the hanafuda earrings and the demon girl who had somehow slipped his absolute control. They were a persistent, irritating anomaly.

But this?

This was not just an anomaly. This was a calculated threat.

“Not only the Kamado siblings,” Muzan hissed to the empty air, his voice dripping with pure, unadulterated venom. “But now… something new is brewing among them.”

“Nakime,” Muzan commanded, his voice echoing through the endless halls, dark and heavy with lethal intent.

Twang.

“Summon the Upper Ranks,” Muzan ordered, a cruel, vicious sneer curling his lips. “It seems the demon slayers have acquired a new plaything. I want every shadow in this country searching for the source of this compound. I want to know who is thinking for them.”

Muzan’s red eyes burned like hellfire in the dark.

“And when you find the one who created it… Bring them to me. Alive.”

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大正コソコソ噂話 — Taishō Kosokoso Iwasubanashi

Tengen, despite his flamboyant bravado, possesses incredibly sharp survival instincts.

After returning to his private estate to formally begin his retirement, he sat his three wives down for a very serious, deeply unflamboyant family meeting.

“Listen to me carefully,” Tengen told Suma, Makio, and Hinatsuru, looking them dead in the eye. “If you ever visit the Butterfly Estate, you can spar with Aoi. You can talk to Kanao. You can even pet the muscle mice.”

He shuddered, rubbing his remaining arm where a phantom chill still lingered from the look the Insect Hashira had given him.

“But you must never, ever cross Kocho when it comes to her love life. The woman is absolutely terrifying.”

A/N

I just knew that Tengen Uzui… Tengen is his first name, Uzui is his last name… Ah… (Previous chapters, I referred to him as Uzui in narration, when it was supposed to be Tengen…).

ALSO! Quick chapter, to establish what’s going on… Huhuhuuuuu, what will happen to reader?! ;0;