One Piece: My Crew is from Other World - Chapter 153: Ryuunosuke’s Response and Arrangements

One day, when a novelist woke up from a restless sleep,he realized that he had transformed into his 12-year-old self.

On the surface, he is the aloof and standoffish patriot whose sole purpose is to serve the nation. On the darker side, he is an invincible, powerful and mysterious man.

“Martial Arts World...” Death murmured, shocked by the turn of the events. How could he, primordial being of the afterlife, get tricked by a mere human? Not just a mere human, but also earthling, race that was weakest of the twenty realms. Death realized the extent of his mistake. An earthling had just jumped into the river of the reincarnation, where he definitely didn’t belong. It was too late. The damage has been done. The matter was now out of his hands. “Kiernan Hunter...” ... Remake of the Martial Arts System, and while the concept stays the same, the story is completely different. A few names, etc, stays the same, but mostly whole new story.

When an S-class elite assassin-raised captain of a special ops suicide squad comes home from a high-stakes Africa mission, he finds himself offered something that could potentially set him up for life- a curious assignment that he could use to finally exit his days of war and slaughter.

Then placed into a high-school setting, Lin Yi is tasked by the chairman of a top-tier multi-billion company with bodyguard duty for non-other than his own daughter, a certain little Miss of said high-school.

His enemies, once ranging from drug lords, mafia bosses, political figures, and national leaders, are soon replaced with spoiled kids who happen to have rich papas and mamas, and Lin Yi finds his intense expertise and high-threat skillset misused, and very underwhelmed…

But he does get a harem cast as diverse as his old enemies, so Lin Yi decides that, for the sake of messing around with girls as an invincible entity in a down-leveled environment, leaving his bloody and death-filled war days behind is something he’d definitely want to strive for.

- Description from Novelupdates