As a child, Monkey D. Luffy dreamed of becoming King of the Pirates. But his life changed when he accidentally ate the Gum-Gum Fruit, an enchanted Devil Fruit that gave him the ability to stretch like rubber. Its only drawback? He'll never be able to swim again--a serious handicap for an aspiring sea dog! Years later, Luffy sets off on his quest to find the "One Piece," said to be the greatest treasure in the world...

Luffy and his crew befriend some of the exotic mer-people on Fish-Man Island, a beautiful and dangerous underwater civilization. They learn that while some on the island are working toward a better relationship with humans, the Fish-Man Pirates are attempting to grasp ultimate power. Luffy and the Straw Hat Crew step into battle once again!