The portable action-RPG prequel tells the tale of Terra, Ventus, and Aqua as the trio faces "a crisis affecting worlds far beyond their own," including those of Disney's Lilo & Stitch, Sleeping Beauty, and Snow White.

Meanwhile, Keyblade Master Xehanort has gone missing--a plot thread that should help explain how Xehanort ended up as the main antagonist of the Square-Disney series.

In addition to the game itself, September 7 will the release of a "KINGDOM HEARTS Birth by Sleep PSP Entertainment Pack." The bundle will only be available via GameStop in North America, and will include a "Mystic Silver" PSP-3000, Kingdom Hearts: Birth by Sleep on UMD, an unannounced and unrelated movie, and 4GB Memory Sick PRO Duo.

To cap off today's announcements, Square passed along a trailer of the game: