One Piece TV Special: The Detective Memoirs of Chief Straw Hat Luffy

Aired after Episode 253 - In an alternate reality world that takes place in 19th century Japan, Luffy acts as a member of the secret police. This is made up of two adventures. In the first, Buggy makes trouble in the town. In the second, a mysterious girl named Vivi appears. This special contains several cameos from characters throughout the entire series. As of episode 424 there are now seven episodes in this special.(onepiece.wikia)