As the progenitor of demons, he controlled their lives, their thoughts, their very existence.
Yet he had completely failed to notice that Akaza's memories had been tampered with.
That meant whoever was hiding in the shadows possessed the terrifying ability to override his bloodline control and interfere directly with the mind itself.
The opponent had deliberately spared Akaza on the Mugen Train, feeding him false information to lower his guard… and lure more Upper Ranks to their deaths.
What a ruthless scheme. What terrifying cunning.
"That human… that lightning swordsman…"
Muzan's breathing grew uneven.
He recalled the young man with pitch-black pupils from Akaza's memories.
Now, it seemed those eyes had not held the spirit of a swordsman—
But the cold amusement of a predator watching its prey.
If even Upper Rank Three could have his memories altered without realizing it, then if he were to face that monster himself…
Kibutsuji Muzan took a step back.
He had survived for a thousand years not through strength alone, but through an instinct for danger sharper than anyone else's.
When he had encountered Tsugikuni Yoriichi, he had split apart and fled without hesitation.
And now..
That same sense of impending doom had returned.
"Kokushibo, Doma, Akaza."
Muzan turned his back to the three remaining Upper Ranks. His voice was cold once more, but now carried an undeniable resolve.
"Cease all hunting and reconnaissance. From this moment on, all of you will remain within the Infinity Castle. Without my orders, no one is to step outside."
Doma froze, unable to hold back his question.
"Muzan-sama… what about the search for the Blue Spider Lily?"
"I will have the lower demons continue the search!" Muzan snapped, turning his head sharply, his plum-red eyes filled with darkness. "Your only task now is to stay within the Infinity Castle and grow stronger!"
"A variable has appeared within the Demon Slayer Corps. Until I uncover its nature—or until I complete my own evolution—none of you are to throw your lives away!"
Even if it meant being called a coward, he would not provoke that mysterious swordsman now.
As long as he remained hidden within this layered dimensional space, the Demon Slayer Corps would never be able to find him.
Time was on his side.
Ten years. A hundred years.
Even if he waited until that monster died of old age, he would still be the one standing at the end.
"Nakime. Seal all entrances to the Infinity Castle."
Ting~!
At his command, the crisp sound of the biwa echoed once more.
The entire space fell into a silent, dormant stillness.
…
Meanwhile, at the Swordsmith Village,
The sun was warm, the breeze gentle.
Compared to the suffocating tension within the Infinity Castle, everything here felt so peaceful it made one drowsy.
"Help! Haganezuka-san! I know I was wrong! Please don't cut me with a kitchen knife!"
Tanjiro, with several swollen lumps on his head, clutched his newly reforged Nichirin Blade and ran for his life along the village road.
Behind him, Haganezuka Hotaru, still wearing his Hyottoko mask, chased relentlessly with two gleaming kitchen knives, like a furious butcher.
"You sword-breaking bastard! I'll turn you into minced meat today!"
On the corridor, Rin held a cup of hot tea, watching the familiar daily chaos unfold, and shook his head with a helpless sigh.
Three days had passed since the deaths of Upper Rank Four and Upper Rank Five.
During that time, the swordsmiths had worked day and night. Not only had they reforged Tanjiro's blade, but they had also thoroughly repaired and maintained Zenitsu's and Inosuke's weapons.
The Love Hashira, Kanroji Mitsuri, and the Mist Hashira, Tokito Muichiro, had already departed yesterday to return to their respective duties.
Before leaving, Muichiro had approached Rin. Though he said nothing, there was a newfound clarity in his eyes—he had clearly rediscovered the reason he first took up the sword.
"If you're done watching, pack up and get ready to leave."
Rin set down his teacup and called out to Tanjiro, Zenitsu, and Inosuke as they ran past the corridor.
...
Half an hour later, at the village entrance,
A Kakushi member, Goto, had been waiting for some time. The moment he saw Rin approach, he straightened instantly, barely daring to breathe.
"R-Rin-sama! Would you like me to prepare blindfolds?" Goto asked nervously, swallowing hard.
"What do you think?" Rin glanced at him sideways.
"U-understood! Please leave it to me!"
Relieved, Goto quickly took out three strips of black cloth, tightly blindfolded Tanjiro, Zenitsu, and Inosuke, then hoisted Tanjiro over his shoulder like a sack and dashed off into the forest, while two other Kakushi members picked up the two boys.
Rin followed behind at a leisurely pace, one hand in his pocket.
The return journey was uneventful.
With no interference from the Upper Ranks, Rin treated it as a casual walk through the mountains.
As he mentally reviewed the points he had earned over the past few days, he felt quite satisfied.
That old schemer Muzan was likely so frightened that he had sealed off the Infinity Castle completely.
For a while, he wouldn't dare send anyone out.
Which meant..
Rin would have a rare period of peace and quiet.
At dusk, the orange-red glow of the setting sun bathed the white walls and black tiles of the Demon Slayer Corps headquarters in warmth.
...
The Butterfly Mansion.
From the kitchen, the aroma of food drifted out—the rich scent of grilled saury mingling with the savory fragrance of miso soup, made all the more appetizing by the cool evening breeze.
Kochou Shinobu stood at the stove, dressed in a light purple casual kimono with a white apron. She skillfully flipped the tamagoyaki in the pan with practiced ease.
"Shinobu-sama, the logistics department reports that the team returning from the Swordsmith Village has already entered the mountains. They should arrive in about half an hour."
Kanzaki Aoi walked in carrying freshly washed vegetables as she delivered the update.
"Understood."
Shinobu plated the golden tamagoyaki. Though her movements remained steady, her gaze drifted again and again toward the courtyard gate beyond the window.
It had been nearly five days since he left.
Although he had said before departing that no demon could kill him, those were Upper Ranks—beings even Hashira treated with caution.
Over the past few days, she had appeared busy preparing medicine in the laboratory, but whenever she paused, her thoughts were filled with that infuriatingly confident face of his.
"If you come back missing even a single hair, just see how I deal with you…"
She muttered under her breath.
"Deal with who? I haven't even stepped inside, and someone's already talking about me."
A lazy, teasing voice came from the kitchen doorway.
Shinobu froze, then turned sharply.
Rin leaned casually against the wooden frame, his black haori draped over his arm. His gaze fell on Shinobu, apron-clad and holding a spatula, and a faint smile curved at his lips.
He looked completely unharmed. His clothes were even spotless, as if he had merely gone out for a stroll.
"You…"
Shinobu opened her mouth, but all the questions she had prepared—whether he had been in danger, whether he had encountered the Upper Ranks—were swallowed the moment she saw his relaxed expression.
She bit her lower lip, suppressing the surge of relief in her chest, and let out a soft snort.
"You chose your timing well. Did you follow the smell of food back?"
Rin walked over, reached out, pinched a piece of freshly made tamagoyaki, and tossed it into his mouth.
"Tch… hot."
He chewed twice before nodding. "Just the right amount of salt. Looks like your cooking hasn't gotten worse these past few days."
"Using your hands to grab food—what are you, a wild boar? Go wash your hands!"
Shinobu slapped his hand away as he reached for another piece, glaring at him, though the faint smile at the corner of her eyes betrayed her mood.
Rin didn't mind in the slightest. Instead, he took the opportunity to catch her wrist and pull her into his arms. Lowering his head, he pressed a light kiss to her cheek, still faintly carrying the scent of cooking.
"I'm back."
The spatula in Shinobu's hand nearly slipped from her grasp. Her face flushed instantly as she struggled to push him away.
"Aoi is still here! You shameless man!"
In the corner, Aoi had already turned away, covering her eyes while chopping vegetables, loudly muttering to herself.
"I didn't see anything! I am a cabbage! Just a cabbage!"
Dinner that evening felt especially warm.
Tanjiro and the others had long since collapsed in their rooms, exhausted after being carried all the way back by the Kakushi. Only Rin and Shinobu sat at the table.
Rin briefly recounted what had happened at the Swordsmith Village, glossing over the details of the battle and simply mentioning that he had dealt with Upper Rank Four and Upper Rank Five along the way.
Even though she had been mentally prepared, Shinobu still drew in a quiet breath.
Two Upper Ranks, eliminated so casually.
Just how many hidden cards did this man still have?
"For the time being, Muzan should stay quiet," Rin said, setting down his bowl and wiping his mouth.
"Then we can finally have a moment to breathe."
Shinobu rested her chin in her hand, gazing out at the moonlight beyond the window.
"Yeah."
Rin leaned back in his chair, watching her soft profile in the gentle light.
"It's nice to take a break from all the fighting. Come with me to town tomorrow. I heard a new wagashi shop opened. Eating your cooking every day, I need a change of pace once in a while."
"You think my cooking is bad? Then starting tomorrow, you can cook for yourself."
"I only handle the eating. If you go on strike… I'll just have to eat you instead."
____
12 Advance chapters:Patreon/slept01