Yokozuna (ヨコヅナ Yokozuna) is a giant sumo-wrestling frog who was once the friend and pet of the legendary shipwright Tom until Tom's execution. After losing his dear friend, Yokozuna began swimming around the waters near Water 7, often blocking the Sea Train in an attempt to stop it. This behavior is believed to stem from his desire to become stronger so he can protect those he loves.
When first introduced, Zoro spotted him from the Going Merry performing this routine. After informing the crew about the giant frog swimming like a human, Luffy decided to alter their course slightly to capture the frog for a barbecue meal. Later, while the Straw Hat Pirates, Galley-La Foremen, and Franky Family were heading towards Enies Lobby on the Rocket Man, Yokozuna tried to stop them but ended up aiding their mission to rescue Franky and Nico Robin.
On Enies Lobby, Yokozuna took on the role of guarding the courthouse against government agents, holding his ground until the Jurors attacked. He was saved by the giants Oimo and Kaashii, who joined him in protecting the courthouse. Yokozuna then boarded the sea train with the Franky Family, Galley-La workers, and the giants, returning to Water 7. He was recently seen in a "where are they now" title page, no longer challenging the Sea Train.
Franky taught Yokozuna how to swim using the crawl stroke. First Appearance: Chapter 322; Episode 228.
http://onepiece.wikia.com/wiki/Yokozuna
