General info :
Kairi is the main female protagonist of Kingdom Hearts, and the best friend of Sora and Riku. She is a non-playable character in most games of the series, but debutes as a playable character in the Re Mind scenario of Kingdom Hearts III. As one of the seven Princesses of Heart, she is cast adrift from her homeworld of Radiant Garden at a young age as part of Xehanort's experiment to locate the key bearer, which eventually brings her to the Destiny Islands, piquing Sora and Riku's interest in other worlds. In Birth by Sleep, it is revealed that her arrival on the islands is the result of an encounter with Aqua, who gives the four-year-old Kairi a protective charm to shield her from the darkness as well as Kairi gaining the ability to wield a Keyblade after touching the one belonging to Aqua.