Muzan savored the dessert of matcha flavor which her husband had brought back. It was her favorite dessert. Her lips were tinted green from indulgence, since she had already had ten of them.

On her way to wash her face, Muzan discreetly paid attention to any movements from Teru's room, making sure he had fallen asleep.

Before long, Muzan, with hands still damp from splashing water, returned to her room and opened the window.

A small vial dropped down from above. Then, two tiny, deformed arms emerged from its base, crawling to Muzan's feet.

"Muzan-sama!"

The fifth of the upper-rank demons, Gyokko!

"How is the plan I tasked you with going?" Muzan spoke with an icy tone.

"We've successfully infiltrated half of the noble families, including the Takeda, Chiba, and Minamoto..."

"Excellent. Keep it up this way."

She smirked, satisfied with her own idea, a plan she named "Infiltration." The plan was brilliantly simple: Gyokko would carry her blood and discreetly introduce it into the diets of influential nobles, subtly and slowly transforming them into demons under her control, who could help Muzan in eradicating the Demon Slayer Corps.

Why hadn't she thought of such a method over the past few centuries? Muzan berated herself. She should have harnessed the power of humans themselves to deal with humans.

"Muzan, who are you talking to?"

Teru yawned as he knocked on the door.

A hint of panic flashed in Muzan's eyes. Swiftly, she tossed the bottle out of the window, watching it shatter upon impact. Gyokko seemed bewildered, but a stern glare from Muzan prompted it to sprout several small hands and crawl. It quickly vanished down the street.

...

The Demon Slayer Corps was a solemn organization with a single mission: to eradicate demons. Yet now, there were members protecting demons.

At the headquarters of the Demon Slayer Corps.

Tanjiro Kamado was bound and placed in the courtyard. Upon awakening, he found Hashiras gathered around him, their expressions grim.

He understood the dillema he was in. He had committed the greatest taboo of the Demon Slayer Corps: harboring a demon.

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Even if it was his sister, and she had never eaten any human flesh, it was unforgivable. The boundary between demons and humans must remain clear.

Tomioka Giyu was somewhat isolated from the other Hashiras. However, Shinobu still stood beside him. So there were two of them isolated then.

Tomioka Giyu closed his eyes and waited calmly.

Shinobu seethed inwardly. Can't this man see that I'm trying to strike up a conversation? Nevertheless, anger aside, she stood beside him.

Before long, Himejima Gyomei and Kagaya emerged from behind a folding screen. The Stone Hashira carried a box, placing it on the floor beyond the reach of the sunlight.

The Hashiras each offered a respectful gesture to their leader.

"No need for formalities. Let's get straight to the point. The agenda for today’s meeting is to handle Tanjiro and his sister Nezuko, who has turned into a demon."

Wind Hashira, Sanemi Shinazugawa, went to the box from a kneeling position in an instant. His blade punctured it, then withdrew, bringing forth a vivid red splash of blood.

The sudden pain startled Nezuko from her slumber, eliciting a pained cry.

"Nezuko!"

Although bound, Tanjiro rose with fiery determination, his eyes burning like an intense flame.

"Don’t you dare to harm my sister!"

With great determination, he lunged at the Wind Hashira, even in this disadvantageous situation, resolved to protect his kin.

But how could he, with his hands bound, inflict any harm on a Hashira?

Wind Hashira was about to kick him. Yet, unexpectedly, Tanjiro leaped into the air, landing a tough headbutt that left Shinazugawa momentarily dazed.

Holding the box shielded on his back, blood trickling from his forehead, Tanjiro secretly struggled to free his bound hands.

Love Hashira and Shinobu covered their mouths, trying not to burst into laughter.

Sound Hashira, Uzui Tengen, sighed and shook his head.

"Shinazugawa! As a Hashira, you got taken down by a headbutt?"

"You...!"

“Enough!”

Himejima Gyomei's voice cut through.

Stone Hashira, Gyomei, was the strongest and most widely respected Hashira. Therefore, after standing up, the Wind Hashira glared at Tanjiro fiercely but refrained from further action.

The Hashiras mostly agreed that Nezuko, as a demon, should be executed immediately. Only Tomioka Giyu remained silent.

Seeing this, Kagaya, produced a letter and began to read it aloud before the assembly. The contents of the letter were a plea from the former Water Hashira, Giyu's master, and the current Water Hashira, Tomioka Giyu. They offered their lives as assurance, entreating the members of the Demon Slayer Corps to grant Tanjiro and Nezuko a chance to prove themselves.

The Wind Hashira, Shinazugawa Sanemi, cut his hand and presented it before the injured Nezuko, attempting to tempt her with the taste of human blood.

Witnessing this scene, Gyomei, who had always been compassionate, did not intervene. It wasn't just out of concern for demons, but he had grown utterly disillusioned with human nature, particularly that of children, after the incident ten years ago that led to his wrongful imprisonment. He could have sentenced to death if it weren’t for Kagaya’s protection. The bitterness and repulsion ran deep within him.

Surprisingly, Nezuko resisted the primal urge to feed on the human blood before her, even as the Wind Hashira tantalizingly presented it.

The Hashiras had to acknowledge that Nezuko might be a unique kind of demon, one who abstained from consuming humans. They reluctantly agreed to postpone her judgment.

As the Hashira dispersed, a guard rushed over to Himejima Gyomei. "Gyomei, someone is here to see you. It's Doctor Watanabe, an acquaintance of yours."

Curiosity and surprise in his eyes, Himejima Gyomei walked toward the entrance. In the sunlight stood a tall and handsome young man, a smile on his lips, clutching a letter.