One Piece: Kaizoku Musou is an upcoming collaboration between Namco Bandai and Koei Temco.
It's the Musou hack-and-slash series, but with a One Piece spin. In years past, Koei and Namco Bandai collaborated to create Gundam Musou, a Gundam meets hack-and-slash Dynasty Warriors style game.
The quality for the embedded trailer above isn't so hot. To see a better quality one, click through the link below.
The game currently does not have a release date. It is slated for the PS3.
One Piece [VJump]