One Piece: I Became Luffy's Younger Brother

Jiang Dayu inexplicably transmigrates to the world of One Piece, but he has never read the story of the pirates. Fortunately, with the help of his golden finger, he can use his clever mind to guess how the story goes. Later, he obtains the Gasu Gasu no Mi, and can finally fulfill his wish from his past life: making round pills...