Is One Piece: Umi no Heso no Daibouken-hen hentai?

TV Special · 2000 · 1 episodes · PG-13 - Teens 13 or older

Action, Adventure, Fantasy, Shounen

The Straw Hats encounter a city in the middle of a whirlpool, called the Ocean's Navel, that is being destroyed by giant monsters. These monsters supposedly protect a treasure capable of granting wishes, but in the process of defeating these guardians, the crew ends up releasing another evil. (aired after Episode 53) (Source: Wikipedia)