
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. It is a prequel to the original Kingdom Hearts, taking place ten years before. The game utilizes an overhauled battle system different from previous games in the series with new elements. 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 non-Japanese versions.

The game was released on UMD in Japan on January 9, 2010, in North America on Septemand in the PAL regions on September 10, 2010.

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 for the PlayStation Portable, serving as the sixth installment in the Kingdom Hearts series.
