The PSP-exclusive action RPG is a prequel to the original Kingdom Hearts for the PlayStation 2, telling the story of three youths - Terra, Ventus, and Aqua - who have been training under Master Eraqus to prove that they, too, exhibit the Mark of Mastery. They will soon find themselves in the middle of a crisis affecting worlds far beyond their own as another Keyblade Master, Xehanort, goes missing.

The Kingdom Hearts series merges a Square-Enix created universe with popular characters and locations from various Disney franchises.

• An essential piece to the KINGDOM HEARTS series arrives on the PSP system: From world renowned creator and character designer Tetsuya Nomura comes the latest installment in the beloved KINGDOM HEARTS series. The vibrant and colorful KINGDOM HEARTS world comes to life through stunning graphics in 16:9 widescreen presentation, made possible by the PSP system hardware.
• Disney worlds and characters new to the KINGDOM HEARTS series: Disney worlds and characters never before seen in KINGDOM HEARTS, such as Enchanted Dominion (Sleeping Beauty) and Castle of Dreams (Cinderella) will make their first appearances in KINGDOM HEARTS Birth by Sleep.
• Three distinct gaming experiences through the eyes of three protagonists: Unravel the mystery surrounding the origin of the KINGDOM HEARTS saga through the tales of three unique characters - Terra, Ventus and Aqua. The whole story is revealed only after playing through with all three characters.
• An action-packed combat system with intuitive controls: The familiar action-packed experience that KINGDOM HEARTS fans have come to embrace returns with an enhanced battle system, with all new features such as Command Styles, Command Decks, Shotlocks and Dimension Links. KINGDOM HEARTS Birth by Sleep is the most advanced KINGDOM HEARTS title to date.
• Four exciting multiplayer modes: Share the excitement and fun with your friends with four brand-new multiplayer modes: Versus, Arena, Command Board and Rumble Racing.
• New game features: The North American release will include a number of new features including Crown Stickers, an extra boss and additional multiplayer options.