Demon Slayer: The Ultimate Defense System

Seeing Shinobu Kocho's hostile stance, Yohan spoke in a calm, measured tone.

"Shinobu, please, let me explain first."

"I'd love to hear what kind of excuse you've got," Shinobu snapped, her eyes full of fury as they locked onto his.

"Tamayo and Yushiro have already overcome the demon's instinct to devour humans. They now survive on small quantities of blood from blood bags."

"That doesn't change the fact that they are demons!" she shot back.

"They're also fighting to destroy Kibutsuji Muzan. In fact, they risked coming here—into the heart of the Demon Slayer Corps—for that very goal."

"You do realize what that means, don't you? For demons like them to come here, where they're surrounded by swords ready to cut them down?"

"So what? All they're doing is researching medicine. I can do that myself," Shinobu retorted, arms crossed tightly.

"Tell me, Shinobu. Do you kill demons because they kill humans—or simply because they are demons?"

"I—of course it's because they..." she started, but her voice trailed off.

Yohan didn't interrupt. He simply continued, "Also, your Lord has already given his approval."

"Hmph! If the Master has approved it, then... fine. Whatever," she grumbled, clearly reluctant.

"But if I notice even the slightest sign of trouble from them, I'll cut them down myself," she added fiercely, though her tone no longer held the same iron certainty as before.

In truth, Yohan's words had already reached her. Shinobu just didn't want to admit it out loud. So, even though she was already swayed, she still had to throw in a sharp parting line for pride's sake.

Yohan watched her—so obviously persuaded yet pretending to remain defiant—and found this version of Shinobu oddly endearing. More than that, he was relieved. The fact that she hadn't reacted violently when Tamayo and Yushiro revealed their identities as demons showed growth. She was changing.

Just then, Shinobu's older sister, Kanae Kocho, returned with the others and happened to witness the scene.

Kanae smiled softly and said teasingly, "Shinobu, I never thought I'd see the day you started agreeing with your big sister's way of thinking."

"Hmph! I—absolutely have not!"

"Oh? Really now?"

"I haven't! I swear I haven't!" Shinobu turned her head away, cheeks faintly red, refusing to continue the conversation.

From the background, Tamayo stepped forward, emotion shimmering in her deep eyes like mist. She bowed deeply before Yohan and said softly, "Thank you, Yohan-kun."

She and Yushiro had returned from their assigned rooms just in time to hear the entire conversation between Yohan and Shinobu.

Tamayo fully understood Shinobu's hatred for demons—after all, she too had done things in her past she could never forgive herself for. So she didn't blame Shinobu's hostility.

What she hadn't expected was for Yohan to speak such words on her behalf. For someone to treat her as human again, despite her past and her nature—it was something she had long given up on. To her, Yohan's acceptance was more than kindness; it was redemption.

Yohan didn't say anything in return. He simply reached out and patted her gently on the shoulder.

Perhaps being understood was, in itself, a kind of salvation.

"Hmph..." Yushiro stood off to the side, glaring at Yohan as he exhaled a long, irritated breath through his nose. But for once, he didn't hurl insults.

After all, Tamayo-sama was expressing gratitude toward Yohan, and even Yushiro had to admit: the man wasn't so bad.

...Though if he'd just stand a little farther away from her, that'd be perfect.

"Ehehe~"

Kanroji giggled at the whole scene, her face beaming with joy.

She knew Yohan would handle things perfectly. As expected, her Yohan was the best!

With everything settled, Tamayo and Yushiro began living at Butterfly Mansion under Kanae's arrangements. Meanwhile, Yohan and Kanroji decided to stay a while longer and await the upcoming Hashira meeting.

In the short time they had been there, the members of Butterfly Mansion gradually realized that these two demons were different from the monsters they had battled in the past. Tamayo and Yushiro felt more like people than demons, and slowly, the staff began to accept them.

…

Time passed day by day, and life at Butterfly Mansion returned to its usual rhythm.

As the primary recovery and rehabilitation facility under Kanae's care, the mansion was always busy treating injured Demon Slayers. Everyone had their hands full with their respective duties.

Everyone except Yohan.

At that moment, he was lounging lazily in a reclining chair in the courtyard, soaking in the warm sunlight.

Training? Out of the question. He was relying on his system to get stronger. Hard work was never part of the plan.

Yohan sighed contentedly, enjoying this rare moment of peace.

"Ahhh, this is the life..."

But before he could even finish his thought, a lively girl with three long, pink braided pigtails bounced up beside him.

"Yohaaaaaaan~~ I want you to spar with me!" Kanroji tugged at his sleeve, her voice drawn out in a sugary whine like a child begging for candy. Her pale green eyes sparkled with enthusiasm as they blinked up at him.

"Alright, alright, I'm getting up..." Yohan sighed with a smile.

How could he ever say no to her?

And so, the two began a light sparring match in the courtyard. Though, truthfully, it was more of a one-sided session where Yohan stayed on the defensive and let Kanroji take the lead, using each exchange as a chance to point out areas she could improve.

The gentle rhythm of blades clashing under the spring sun brought warmth to the mansion—a moment of peace before the storm sure to come.

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