With his mechanical mastery skill, Ron had completely restored the broken Yorichi Type Zero puppet.
When Kotetsu witnessed the now fully-repaired puppet perform an entire sword technique with seamless grace, he was utterly floored by Ron’s craftsmanship.
Then and there, he dropped to his knees, forehead pressed firmly to the ground before Ron.
"Master Ron! Please, take me as your disciple! I’m willing to do anything!"
In the end, Kotetsu still failed to get Ron to accept him as a disciple before he left the Swordsmith Village.
On the fifth day since arriving at the village...
Ron and Shinobu returned to the Demon Slayer Corps headquarters.
Mitsuri Kanroji had received a mission the day prior and had already departed the village ahead of them.
After returning to HQ, Sanemi Shinazugawa, whose injuries had mostly healed, immediately came to Ron. Bowing his head, he sincerely apologized for his past rudeness, ignorance, and reckless behavior, and thanked Ron for saving Kagaya Ubuyashiki’s life.
Ron had never taken the matter to heart in the first place, so he simply waved it off.
Ron went back to his laid-back days—sipping tea in the daylight, sampling fine liquor, nibbling on snacks, and casually offering sword guidance to Kanao.
Shinobu spent her days at the Butterfly Estate tending to patients. At night, she’d come to Ron’s place to spar with him. Under the crushing pressure of his swordsmanship, she experienced firsthand what it meant to step into the realm of Transparent World.
Several peaceful days passed in this manner—three or four in total—before news shattered the calm.
"Lower Moon demons have appeared on Natagumo Mountain!"
"Tanjiro and his companions have already encountered them!"
Upon hearing that many Demon Slayers had been poisoned by spider venom and required emergency aid, Shinobu and Kanao immediately set off with a squad of Kakushi to assist.
Meanwhile, in the courtyard near the Butterfly Estate...
Ron lounged beneath a cherry blossom tree, reclining in a chair, eyes lazily trailing the drifting clouds above.
Natagumo Mountain, huh...
Yeah, it’s about time for that arc to kick off...
Tanjiro should be learning the Hinokami Kagura soon. I’ll help him refine it into Sun Breathing next time we meet...
[Ding! System upgrade complete.]
Suddenly, a long-forgotten mechanical voice echoed in his mind.
Ron blinked, startled.
[The Sign-In System has been upgraded to: Dimensional World Ultimate Sign-In System.]
Today’s the 30th day!
His usually tranquil heart surged with excitement.
Does this mean I can finally go back?!
[Analyzing world structure... Host currently located in Demon Slayer World – Demon Slayer Corps Headquarters. Location is eligible for sign-in.]
[Initiate sign-in for corresponding rewards?]
[Ding! Sign-in successful. Rewards received: +10 Vitality, +10 Mental Strength
Acquired: Perfect-Grade Demonization Serum ×1, Perfect-Grade Humanization Serum ×1]
"Perfect-Grade Demonization Serum... and Perfect-Grade Humanization Serum?"
Ron blinked in surprise.
After examining their descriptions, he immediately understood.
One could transform a person into the kind of perfect demon Muzan had only ever dreamed of.
The other could turn any demon into a perfect human being.
Well now... that’s unexpectedly useful.
Even Ron couldn’t help feeling a little tempted as he studied the Demonization Serum’s effects.
A demon that fears neither sunlight nor decapitation, that can regenerate from a single surviving cell, and can alter its form at will...
Indeed, such a being could rightfully be called the ultimate, flawless lifeform.
However, becoming a demon meant abandoning his humanity.
And deep down, Ron still felt a twinge of resistance to that.
"...I’ll hold onto them for now. We’ll see later."
With that thought, Ron stashed away the vial containing the shimmering blood-red liquid—both the Perfect-Grade Demonization Serum and the Perfect-Grade Humanization Serum—into the newly reopened System Inventory.
He had more pressing questions to ask right now.
"System, can I still return to the One Piece world?"
The moment he asked that question, a rare emotion stirred in Ron’s chest—unease, and even... nervousness.
[Ding! Coordinates of the One Piece World have been located using your previous sign-in traces. After computation, three possible methods to return have been determined.]
"Three methods?! That’s great!"
Ron’s face lit up with delight. "Quick, tell me what they are!"
[Method One: The host may break through the dimensional wall with sheer power and traverse the time-space vortex with their physical body. Based on the coordinates, the system will guide the host to the dimensional membrane of the One Piece world. Once the host breaks through that membrane, re-entry is possible.]
Ron’s expression instantly darkened. "Break through the dimensional wall? Cross a time-space vortex physically? Do I look like I have that kind of power?! And how long would it even take to cultivate that level in this world?!"
[Method Two: By supplying an immense amount of time-space energy, the upgraded system can directly teleport the host back to a previously visited world.]
"That sounds promising, but... where in this world am I supposed to find a massive amount of dimensional energy?"
[Method Three: By consuming a specific number of Sign-In Points, the upgraded system can teleport the host to an adjacent alternate world.]
"Sign-In Points? What’s that?"
[Each successful sign-in earns the host 1 Sign-In Point. Current Sign-In Points: 1.]
"...Only one?" Ron was speechless. "What about all the sign-ins I did in the One Piece world?!"
[Sign-In Points were introduced after the system upgrade. Only sign-ins from this point forward will count. A total of 10 Sign-In Points is required to travel to an adjacent world.]
Ron rubbed his temples, speechless. "So if I teleport to some adjacent world, how exactly am I supposed to make my way back to the One Piece world?"
A faint sense of dread crept into his heart.
Don’t tell me... I’m stuck here forever?
[Rest assured, host. Based on the coordinate mapping, the One Piece world is separated from your current world—Demon Slayer—by only one adjacent dimension.]
The mechanical voice fell silent.
Ron blinked. "Wait... so you’re saying, if I just get through one more world, I’ll make it back to the One Piece world?!"
His eyes lit up instantly. His heart, once knotted with uncertainty, now surged with renewed purpose.