One Piece: This Marine Is a Tough Guy, but He's a Bit of a Jerk

[Slow burn + decisive and ruthless + pure Marines + tough protagonist + swordsman + one heroine]

Luo Yu transmigrates to the world of pirates. In a world overrun by pirates and filled with powerful fighters, he chooses to join the Marines.

Starting at the very bottom, he rises through the ranks and becomes the youngest Marine Admiral in history in just six years!

His terrifying swordsmanship makes people tremble, and his ruthless nature strikes fear into countless pirates.

During the Paramount War, Luo Yu and Akainu fight with all their might to slaughter the pirates. At last, they stand before the dying Whitebeard, and Luo Yu says:

“I've been on the battlefield. I've seen mountains of corpses. I started out as an ordinary man and climbed step by step to the rank of Vice Admiral. Nothing I've seen has ever given me reason to believe that you pirates deserve forgiveness.”

Sengoku: “He may disobey orders, and he can be a little ruthless when completing missions, but Luo Yu is definitely a Marine who believes in justice!”

Vice Admiral Garp: “Damn it, could you stop hunting down my grandson?!”

Luo Yu: “I'm doing it to protect him, Vice Admiral Garp.”

He will bring this pirate-worshipping era to an end with his own hands!