One Piece: With Sign-in System

"!!"

Before the Hashira could even react, the air around them seemed to freeze. A crushing, formless pressure suddenly descended upon their shoulders, weighing on their hearts and minds. The sheer intensity made it hard to even stand.

Wide-eyed and pale, they all looked up in shock.

Standing before them was the black-clad young man, his icy blue eyes looked down upon them—like a god surveying mortals.

Shinobu Kocho stared at him blankly, waves of emotion crashing within her heart.

Just his presence alone… was enough to pin the Hashira to the floor.

This man truly wasn't on the same level as them.

He was terrifyingly powerful—like a god.

The crushing aura pressed down on the room, yet Kagaya Ubuyashiki remained composed—not from physical resilience, but from an inner serenity untouched by fear.

Though blind, he felt it in his bones—something extraordinary had just happened.

"…Mr. Ron, are you angry?"

He asked softly.

"A little," Ron replied casually. "I don't take kindly to being insulted by fools. I've just temporarily disabled his mobility."

His tone remained even. "When I said he was a fool, I wasn't referring to what he said. I meant that he misunderstood my meaning."

"You're right—your current strength isn't enough to defeat Muzan Kibutsuji or the Twelve Kizuki. But strength can grow… and they, too, can weaken."

Obanai Iguro's pupils narrowed.

The others also visibly stiffened at Ron's words.

"…Can our strength really improve that quickly?"

Mitsuri Kanroji asked, unable to hold back her curiosity.

Ron turned to look at Shinobu. "Remember what I told you before? About the Crimson Blade and the Marks?"

Shinobu nodded blankly, still dazed.

Ron said calmly, "If even one swordsman awakens their Mark, others around them will begin to awaken theirs as well. As for the Crimson Blade—it's not just a technique, but a transformation of the Nichirin sword. It can be taught, yes—but mastering it still demands precision, timing, and strength."

Shinobu's eyes slowly widened as realization dawned.

Ron continued, "Right now, Muzan is sending demons to hunt down Tanjiro. If the Lower Moons are killed… there's a good chance the Upper Moons will appear next. When that happens—strike. Eliminating one of the lower-ranked Upper Moons isn't impossible."

He stepped forward, walking up to Kagaya Ubuyashiki. Then, raising his right hand, he held it out over Kagaya's head, palm down.

Everyone's eyes widened in stunned disbelief.

A soft rain of green light began to fall from Ron's hand, gently showering Kagaya's body. His mangled, scar-covered face began to heal rapidly, the disfigurements vanishing at a speed visible to the naked eye.

Kagaya—whose eyes had long been blinded by illness—suddenly felt a warmth and clarity he had never experienced before. The endless darkness in his vision began to brighten, and blurry shapes slowly started to take form.

"W-What is this…?"

Even someone as composed as Kagaya couldn't help but feel like he was dreaming. The world in front of him, once shrouded in darkness, was returning to him.

Muichiro Tokito stared blankly. "Master's… wounds are gone?"

Gyomei Himejima clasped his hands together, tears streaming down his face. "Is this… a divine miracle?"

Tengen Uzui, usually so flamboyant and loud, stood frozen in stunned silence, staring at Kagaya's now-pristine face and clear eyes.

Those grotesque scars, that incurable sickness—he had recovered in a single moment?

"Incredible…"

Kyojuro Rengoku was visibly shaken.

Obanai rubbed his eyes, stunned beyond words.

Mitsuri covered her gaping mouth with both hands, eyes shining with awe and reverence as she stared at the black-clad young man. "A god…! Mr. Ron must be a god!"

Shinobu stood there frozen, her gaze fixed on Ron's back.

As a pharmacist, a poison specialist, a woman of science and logic—what she had just witnessed shattered everything she believed to be possible.

How could such a power exist in this world…?

Ron slowly withdrew his hand, then addressed Kagaya with a calm voice, "I can't completely cure your illness. But I've restored your body to how it was when you were a teenager. It should buy you at least another decade or two."

Kagaya slowly lifted his head, looking up at the black-clad youth before him. His sight had not yet fully returned, and he could only make out a faint outline of Ron's face… but those tranquil, blue eyes—clear as a still lake—were unmistakable.

"Mr. Ron, just who exactly are you?"

"You don't need to know that."

"A clan cursed by fate leads the Demon Slayers, while demons kneel beneath their primordial progenitor. I'm merely here to witness an interesting war unfold with my own eyes. That is the only reason I came to the Demon Slayer Corps headquarters."

As he finished speaking, he cast a sidelong glance at Kagaya Ubuyashiki.

"I didn't heal you for free. I'll be staying here at the headquarters for a while—that will be my payment. And don't spread word of me. I detest being disturbed. If anything comes up, have Miss Shinobu inform me."

With that—

Ron's figure flickered and vanished into thin air.

Leaving only the stunned Hashira behind, frozen in place by the shock of everything they had just witnessed.

…

Butterfly Mansion.

In the courtyard of the Butterfly Mansion, one of the three little girls known for their round, beady eyes—Terauchi Kiyo—was cheerfully humming a tune as she hung out freshly washed futons under the sun.

"Alright! That's the last of them. Sumi, are you done over—"

Just as she turned her head toward her companion—

She froze.

A tall figure had appeared behind her at some unknown point, like a ghost out of thin air.

"KYAAA!!"

Thud!

Kiyo shrieked in terror and tumbled backward.

"What's going on?!"

Hearing the scream, Kanzaki Aoi—dressed in her usual Butterfly Mansion uniform, twin pigtails bouncing—rushed out from inside.

Her sharp gaze immediately landed on the fallen Kiyo… and the unfamiliar black-clad man standing in front of her.

Aoi's eyes narrowed, and her hand flew to the hilt of her Nichirin Blade.

"You! What did you do to Kiyo?!"

"Do? I didn't do anything."

Ron, who had just used his Tenseigan technique to teleport into the area, looked speechless.

But Aoi wasn't waiting for answers.

With a powerful push off the ground, she leapt high into the air and launched a whip-like kick directly at the stranger.

Though she wasn't nearly as skilled as Kanao—Shinobu's personal Tsuguko—Aoi was still a member of the Demon Slayer Corps. She was trained not only in medical care, but also in battle.

Ron tilted his head ever so slightly.

Swish—

Her kick whiffed through empty air.

"What?!"

Aoi's eyes widened in disbelief as she twisted her body midair, landing on the ground in a crouch. Still unwilling to back down, she stomped the ground and reached for her blade, preparing to strike.

But just as her fingers wrapped around the hilt—

A figure appeared between her and Ron, gently pressing down on her elbow to prevent the blade from being drawn.

Kanzaki Aoi blinked in shock.

"Kanao?!"

"Stop."

Kanao's voice was calm and soft.

"This is Mr. Ron. He's… a guest of Shinobu."

"A guest of Shinobu?!"

Aoi's eyes widened even more, as if trying to see if Kanao was serious. Then she turned and stared at the black-clad man behind her, her expression caught between wariness and disbelief.

Meanwhile, Kiyo had already picked herself up, and the other two girls with beady eyes rushed over to her side, worried.

Kiyo, her voice gentle and a little embarrassed, looked toward Aoi.

"Aoi-san… This gentleman didn't do anything to me. I just got startled and fell on my own. I'm really sorry…"