|Kingdom Hearts Birth by Sleep|
|キングダム ハーツ バース バイ スリープ|
Kingudamu Hātsu Bāsu Bai Surīpu
|Publisher(s)|| Square Enix|
/Canada Square Enix
Europe/Australia Square Enix
|Release date(s)|| January 9, 2010|
|Game modes||Single player, multiplayer|
|platforms = PlayStation Portable}}Kingdom Hearts: Birth by Sleep is the prequel to the Action RPG Kingdom Hearts series, released on the PlayStation Portable (PSP) on January 9th, 2010 in Japan, September 7th, 2010 in North America and September 10th, 2010 in Europe. It documents the tale of Terra, Ventus and Aqua, the three Keyblade wielders before Sora, Riku and Kairi, and delves deep into the mysteries of Xehanort, and how Sora and Riku gained their Keyblades.
Like the first Kingdom Hearts and Kingdom Hearts: Chain of Memories/Re:chain of Memories, the theme song is Simple and Clean by Utada Hikaru. A special version was released overseas, adding a number of new features, such as the Unknown boss battle, two new keyblades, new abilities, mini-maps games, and Critical Mode - a difficulty mode even harder than Proud Mode. In September 2010, a Final Mix version was announced in Weekly Shōnen Jump, was released on January 20th in Japan.