One Piece: Pirate Warriors is a spin-off of Koei's Musou franchise based on the manga and anime One Piece. Players take control of one of the crew members of the Straw Hat Pirates and a number of allies as they fight off waves of enemies and defend/take control of select regions on a given map. The game adapts select arcs from the manga storyline in the game's story mode.
The Main Log is a story mode that is faithful to the manga. Players control members of the Straw Hat Pirates in various battles to advance the story. This mode is primarily focused on One Piece protagonist Monkey D. Luffy's journey, but at key points, control will switch to an ally who must complete a set objective.
The Main Log covers the span of time from the beginning of the Romance Dawn arc (Monkey D. Luffy's beginning of his quest to become Pirate King) to the beginning of the New World arc (set after the terrible events at Marineford and a two year time skip). Not all arcs are included, however, and the Main Log skips over select portions of the story including Skypiea and Thriller Bark.
The Another Log mode allows the player to take control of any of the games thirteen characters and do battle over a multitude of stages. The availability of stages on each character's path depends on when they were introduced into the story. This mode can also be played cooperatively, locally or taken online, allowing two players to work together to complete the stage.
Characters can level up by defeating enemies and completing objectives in this mode. If played online, upon completion of a stage the player will receive ranking points. The highest ranking players can be viewed on the leaderboards.
The Challenge Mode sends endless waves of enemies at the player, including bosses. The objective of this mode is to survive for as long as possible. This mode has leaderboard support.
The following characters are playable in the game: