Solo Leveling- Ragnarok - Chapter 256 - 254

Ron finds himself reborn in the world of One Piece, stranded on a remote island in the East Blue. But he's not just any ordinary child—he’s bonded to a mysterious sign-in system that grants him powers with every new location he visits.At his first sign-in, he unlocks the legendary Sun Breathing Technique, along with a boost to his vitality. From Shitmotsuki Village to Skypiea, Enies Lobby to Marineford, Ron travels the world, collecting extraordinary rewards that make him a force to be reckoned with. The Raikiri, one of the 21 Great Grade Swords, Armament Haki, Observation Haki, and more fall into his hands.As Ron steps onto the battlefield of Marineford during the legendary Summit War, the mightiest warriors—Four Emperors and Marine Admirals alike—pause, stunned by his presence. But Ron merely waves them off, “Don’t mind me. I’m just passing through.”Join Ron on his journey across the Grand Line as he signs in at iconic locations, growing stronger with every step. This is not just an adventure—it’s a legend in the making.

Super soldier Su Chen, returned to the city and returned to the city, set off all directions! The king of soldiers that once famous the world, let everyone be convinced!

- Description from xbiquge

During the years of study, no one would associate Jiang Huai with Mingshuang. Mingshuang is the school flower, always at the center of the situation, rich and beautiful, and arrogant. Jiang Huai is always No. 1 in the affiliated high school. The boy’s family background is not good, but he is handsome and indifferent, and he treats others with restraint and alienation. Only Mingshuang knows what he looks like in private. One summer night after the college entrance examination, under the camphor tree…

- Description from Novelupdates

Karl Adelheit, a self-proclaimed ordinary student returning from military service.

And a nobleman who enlisted as a soldier and received Medals of Honor.