The Kingdom Hearts video game series, developed by Square Enix in collaboration with Disney, is set in a universe consisting of numerous self-contained worlds based on intellectual properties from both companies. Most worlds are based on different Disney films, although several original worlds also appear.
The series centers on the character Sora, a boy who searches for his lost friends and encounters Disney and Square Enix characters as he travels between worlds. In the first game, Kingdom Hearts, he fights against the villainous Heartless and seals each world he visits to prevent their return. In Kingdom Hearts II, he helps the residents of these worlds again while searching for his friend Riku. The Kingdom Hearts games have been both critically acclaimed and commercially successful, and the design of the worlds have been praised for their faithfulness to the source material.