Quick, name one of the two absolute top-selling video game systems in Japan! Anyone saying "the PSP" is correct, and its library is full of smaller, more experimental or retro-styled titles that otherwise wouldn't make any money if they were in HD, not to mention Japan's much larger handheld gaming market ("the DS" would also be a valid answer).
Surprisingly, Eiichiro Oda's Jump megahit series One Piece has never been available on the PSP--until now. The newest issue of Jump announced One Piece: Romance Dawn, a turn-based RPG with a menu-driven battle system. Like every other RPG ever made since the dawn of time, players will get stronger through battle, and you'll be able to customize Luffy's stats such as speed and attack strength. The game will be available this coming winter.
So far, those are the only details available--we'll find out more in future updates, and Jump states that the battle system will have more than just basic turn-based battle elements. That would be fine by me--turn-based battle can be pretty stressful at times (see also: Dragon Quest), so it would make for some pretty awesome One Piece fights. What would you like to see in One Piece: Romance Dawn?