One Piece Romance Dawn: Adventure at Daybreak covers a lot more of One Piece than the title suggests. Jump reports the Impel Down arc will also be in the PSP role playing game. In this storyline Luffy and crew break into Impel Down, an underwater prison, to rescue Ace. Jinbe, Buggy, Ivankov, and Bon Kurei will be in the game as NPCs.
In battle, you can use the Grand Chain move in One Piece Romance Dawn to assault enemies with one special technique after another. Namco Bandai also said the Thriller Bark arc is also in One Piece Romance Dawn.