Kagaya Ubuyashiki remained deep in thought long after the meeting had ended.
Although he had already foreseen fragments of the future through the strange intuition carried by the Ubuyashiki bloodline, the images remained incomplete and unclear.
A confrontation between Kokushibo and Muzan Kibutsuji.
A crimson blade reborn after centuries.
And a demon standing at the center of it all.
Nothing about the situation made sense.
The Crimson Nichirin Blade was a legendary weapon said to drastically hinder a demon's regeneration and inflict wounds that even Upper Rank demons feared.
For generations, Demon Slayers had sought the secret behind it.
Yet now, the first person to manifest that legendary power once again was not a human swordsman
But a demon.
The irony was almost absurd.
It was like poison meant to destroy demons somehow being cultivated by demons themselves.
Even Kagaya, who usually accepted fate with calm serenity, found himself unable to fully understand the meaning behind it.
As he sat alone in silence, the sliding door behind him opened softly.
Amane Ubuyashiki entered quietly.
Their children had already fallen asleep, yet she had noticed that her husband remained awake far later than usual.
"Kagaya-sama," she said gently.
Kagaya immediately smiled as though nothing was wrong.
"Amane… you should be resting."
But Amane knew him too well.
Others only saw the graceful head of the Demon Slayer Corps the calm leader who faced despair without fear.
Only she understood how much pressure he carried every single day.
Without another word, she walked beside him and gently embraced him from behind.
"You are forcing yourself again," she whispered softly.
She guided him down carefully until his head rested upon her lap, her fingers lightly massaging his forehead.
The warmth of her touch shattered the composure he had maintained all evening.
Kagaya closed his eyes tightly.
"I may have acted recklessly this time," he admitted quietly.
"The Nichirin Blade alone was already dangerous enough… but the Crimson Blade…"
His voice trembled faintly.
"That power was supposed to belong to humanity."
Now it had appeared in the hands of a demon.
And not just any demon
Kokushibo.
A being powerful enough to rival natural disasters themselves.
Amane listened quietly until he finished speaking.
Then she lowered her head and gently kissed his forehead.
"I trust you," she said softly.
"No matter what fate awaits us, I will remain by your side."
Kagaya slowly opened his eyes.
For a moment, the exhaustion within them faded.
"Thank you… Amane."
He gently held her hand.
Their marriage had originally been arranged to preserve the Ubuyashiki bloodline, yet over the years they had become far more than husband and wife bound by duty.
Back then, Kagaya had merely been a child carrying the burden of an entire organization cursed for generations by Muzan Kibutsuji.
Amane had been the one person who listened to his fears without hesitation.
The one who shared his determination to destroy Muzan and end the curse upon their family forever.
Even now, she remained his greatest source of strength.
The following morning
Tomioka Giyu arrived quietly at the Butterfly Mansion.
Because Kanae had become a demon, exposure to sunlight remained dangerous despite her unusual self-control. As a result, she spent most of her time indoors within the estate.
Fortunately, Kanae required only a minimal amount of blood to maintain herself.
The attendants of the Butterfly Mansion had gradually accepted her existence and voluntarily offered small amounts of blood when necessary.
As Giyu entered the mansion grounds, Kanae greeted him with her usual gentle smile.
"Ara, Tomioka-san. Were you injured during a mission?"
Giyu shook his head immediately.
Then, after briefly scanning the area, he asked in his usual blunt tone:
"Is Shinobu here?"
Kanae's smile deepened slightly.
"She went out to gather medicinal herbs. She should return soon."
Giyu paused for a moment.
"…I see."
Then he turned around and started leaving immediately.
Kanae blinked in disbelief.
"Honestly… Tomioka-san is unbelievably awkward."
Then she laughed softly to herself.
"Still… Shinobu definitely treats him differently from everyone else."
"He's just a socially hopeless idiot."
A rough voice suddenly interrupted from outside the window.
Shinazugawa Sanemi stood there with his arms crossed, his expression full of irritation.
Kanae rested her chin against her hand and smiled teasingly.
"Shinazugawa-san, do you know it's rude to eavesdrop?"
Sanemi scoffed.
"You were talking loud enough for the whole estate to hear. I just happened to pass by."
The moment he finished speaking, he disappeared again like a violent gust of wind.
Kanae merely chuckled quietly.
Some time later, Giyu unexpectedly returned.
In his hand was a delicate butterfly-shaped hair ornament.
"…Could you give this to Shinobu for me?"
Although his face remained expressionless as always, the slight redness around his ears betrayed him completely.
After the events of the previous night, Giyu had become convinced that Shinobu disliked him even more than usual.
Unable to understand how to fix the situation himself, he had reluctantly sought advice from Uzui Tengen.
And according to Tengen
Women appreciated gifts.
Considering Tengen had three wives, Giyu had accepted the advice with complete seriousness.
Kanae stared at him silently.
Tomioka Giyu truly was hopeless.
No wonder he always sat alone during gatherings.
No wonder the other Hashira constantly misunderstood him.
His personality itself was the problem.
Still, Kanae found the situation amusing.
"Why ask me for help?" she asked with a playful smile.
"Because nobody else would help me," Giyu answered honestly.
Kanae nearly laughed aloud.
At least he was sincere.
"Then what do I receive in return?"
Giyu thought seriously for several seconds.
Then he extended the butterfly ornament toward Kanae.
"You can give this to Shinobu."
Kanae immediately became speechless.
His emotional intelligence was somehow even worse than she expected.
After a long pause, she finally sighed.
"…Fine. I'll help you."
After all, Shinobu was still her younger sister.
And despite everything, Kanae genuinely wanted the two of them to get along.
Neither of them noticed that the wind outside the mansion only fully disappeared after Giyu finally left.
Meanwhile
Back at his estate, Kokushibo continued examining the Nichirin Blade resting across his knees.
Every time he attempted to activate the Crimson Blade state, the transformation lasted only an instant before fading away.
Why?
He had already confirmed that physical strength alone was not enough.
Something else was missing.
At first, Kokushibo wondered whether the issue originated from himself.
But he quickly rejected the thought.
Impossible.
If anyone possessed sufficient strength to force a blade into the crimson state, it would certainly be him.
That meant the problem lay elsewhere.
Perhaps the process required more than overwhelming grip strength.
Perhaps body temperature, breathing rhythm, or another unknown factor also played a role.
Eventually, Kokushibo stopped dwelling on it.
For now, the Crimson Blade held little practical importance.
After all, he still had not decided whether he truly intended to oppose Muzan directly.
Besides…
Muzan in women's clothing was admittedly quite beautiful.
That absurd thought briefly crossed his mind before he dismissed it immediately.
More importantly, another issue remained unresolved.
He could no longer contact Nakime through Muzan's blood connection.
That posed a dangerous problem.
Sooner or later, someone would question it.
How exactly was he supposed to explain such a thing?
Should he invent some ridiculous story about consuming a mysterious fruit?
Or drinking from some supernatural river?
As Kokushibo pondered the issue, inspiration suddenly struck him.
"…Wait."
He slowly narrowed his six eyes.
"Why should I explain anything?"
A smile appeared across his face.
Would it not make far more sense for him to act confused instead?
"Why can I no longer sense Muzan-sama?"
"Why has my connection to him weakened?"
In an instant, the entire situation reversed itself.
Satisfied with the idea, Kokushibo immediately decided to test it.
However, after glancing at the blazing sunlight outside, he calmly postponed the matter until nightfall.
Only after darkness fully covered the land did Kokushibo make his way toward the Infinity Castle.
The moment he appeared within the shifting corridors, Muzan nearly lost control of his expression.
Why is he here again?
Among all the threats in existence, Muzan feared Kokushibo the most at that moment.
Not because Kokushibo could kill him outright.
But because neither side could destroy the other easily anymore.
If they truly went to war, the consequences would be catastrophic.
The Infinity Castle would be exposed.
His hiding places would vanish.
And if another monster like Tsugikuni Yoriichi ever appeared in the future…
Muzan's thousand years of survival could end instantly.
For perhaps the first time in centuries, the Demon King experienced something dangerously close to genuine stress.