Chopper's Big Adventure

One Piece: Chopper's Big Adventure (チョッパーの大冒険, Choppaa no Dai Bouken) is a Japanese role-playing game for the Wonderswan handheld featuring characters from the popular anime and manga series One Piece. It was developed by Bandai and released on October 16, 2003 by Bandai Namco.

Plot
One day, the Straw Hat Pirates travel to a mysterious island. While the Straw Hats explore around the island, they all suddenly turn into animals; Luffy into a monkey, Zoro into a tiger, Sanji into a fox, Nami into a cat, Usopp into a kappa, and Robin into a parrot. Only Chopper remains as he was.

It is up to Chopper to not only help the crew to turn back to there original state, but to also figure out the cause of their mysterious transformation.

Gameplay
The game is basically using Chopper to travel and explore dungeons and fight some monsters and bosses. You can also use the other crew as supporting characters to help you fight in the dungeons.

Playable

 * Tony Tony Chopper

Supporting

 * Monkey D. Luffy
 * Roronoa Zoro
 * Nami
 * Usopp
 * Nico Robin
 * Sanji

Trivia

 * In the SBS in Volume 20 Chapter 177, Eiichiro Oda stated that Luffy resembles a monkey, Zoro resembles a shark, Nami resembles a cat, Usopp resembles an armadillo, Sanji resembles a duck, and Robin resembles a crane. However, although volume 20 was already published by the time of the game release, only Luffy and Nami turn into their "right" animal counterparts in this game.