Yes, you're right! One Piece: Pirate Warriors 2 was a downloadable exclusive title for the PlayStation Vita (PS Vita) handheld console. The game was developed by Koei Tecmo Games and published by Bandai Namco Entertainment.
Here's a brief summary:
One Piece: Pirate Warriors 2!
One Piece: Pirate Warriors 2 is a side-scrolling action game that features fast-paced combat and exploration. Players control various characters from the One Piece universe, including Monkey D. Luffy, Roronoa Zoro, and Boa Hancock, as they battle against hordes of enemies and bosses. one piece pirate warriors 2 ps vita download exclusive