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.
The game utilizes an overhauled battle system different from previous games in the series with new elements.
It 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.