Kingdom Hearts - Birth by Sleep [USA]

Kingdom Hearts Birth by Sleep (Japanese: キングダムハーツバースバイスリープ Hepburn: Kingudamu Hātsu Bāsu bai Surīpu?) is an action role-playing game developed and published by Square Enix and Disney for the PlayStation Portable, serving as the sixth installment in the Kingdom Hearts series. The game was released on UMD in Japan on January 9, 2010, in North America on September 7, 2010 and in Europe on September 10, 2010. An international version of the game titled Kingdom Hearts Birth by Sleep Final Mix was released in Japan in January 2011 featuring the changes made in the overseas versions.

The game utilizes an overhauled battle system different from previous games in the series with new elements. The game is a prequel to the original Kingdom Hearts, taking place ten years before. The game centers on the journeys of Terra, Aqua, and Ventus, characters briefly featured in Kingdom Hearts II, in their quest to locate the missing Master Xehanort and protect the worlds from creatures known as the Unversed. The player has access to the three characters' different scenarios when playing.

Development of the game began in June 2005 with parts of the game Kingdom Hearts II Final Mix meant to bring clues of Birth by Sleep. Nomura has referred to the game as "Episode 0" saying that the game is on the same scale and plays as big an importance as Kingdom Hearts and Kingdom Hearts II. The game has been well-received, selling 1.27 million copies worldwide as of November 2010, and receiving positive comments by video game publications.