One Piece is a shonen manga about pirates, but not normal pirates. This is the plot: "A boy named Monkey D. Luffy, inspired by his childhood hero "Red-Haired" Shanks, sets out on a journey to find the legendary treasure One Piece, to become the new Pirate King. To accomplish this, he must reach the end of the most deadly and dangerous ocean: The Grand Line.
Luffy captains the Straw Hat Pirates first through the sea of East Blue and then through the Grand Line. He follows the path of the deceased Pirate King, Gol D. Roger, from island to island on his way to the great treasure One Piece. On his way his crew grows to have a swordsman and first mate Zoro, a navigator Nami, a sniper Usoopp, a cook Sanji, a doctor Chopper, an archaeologist Robin, a shipwright Franky, and a musician Brook.
During the course of the story, the crew contend with both other less moral pirate crews and the Navy. The latter are the subordinates of the World Government, who apparently seek justice by ending the Golden Age of Pirates. Many background story elements involve the delicate balance of power between the World Government and the world's most powerful pirate crews. Also, the Craziest Crew in the world ."
This manga is really funny, and all the charachters (including the villains) are very interesting. If you want to read it, you can read it in this link: