kairi is a friend of Sora and Riku, and is one of the seven "Princesses of Heart". She is an original character created by Tetsuya Nomura for the Kingdom Hearts series. Nomura has stated that Kairi's name can be interpreted as "sea"; the Japanese on'yomi pronunciation of sea is kai . She is voiced in English by Hayden Panettiere in the first two games and Alyson Stoner in Kingdom Hearts Re:Chain of Memories. Risa Uchida voices her in the Japanese version.
Kairi was originally a resident of the Radiant Garden, but was sent to the Destiny Islands by Xehanort a few years before the events of Kingdom Hearts in an experiment to test the connection between a Princess of Heart and a Keyblade bearer. At the beginning of the series, she is fourteen years old. When the Destiny Islands are destroyed by Heartless, her heart is separated from her body and enters Sora's body, leading to him seeing visions of Kairi. Riku, searching for a way to revive her, brings Kairi's comatose body to Hollow Bastion where her status as a Princess of Heart is revealed along with the location of her heart. Learning of this, Sora gives up his heart in order to restore hers back into her body, transforming himself into a Heartless and creating Kairi's Nobody, NaminÚ, as well as his own, Roxas, in the process. Soon after, Kairi finds Sora's Heartless and restores him back to human form. After Xehanort's Heartless is defeated, Kairi is left behind on the reforming Destiny Islands and separated from Sora. Sora promises to return to her with Riku, and Kairi waits on the island for their return.
During Chain of Memories, NaminÚ's memory-altering powers break the memories in Sora's mind as well as those of his friends on the Destiny Islands. In Kingdom Hearts II, Kairi and all of Sora's friends slowly begin to remember Sora, sending a letter she wrote out to sea in hopes that it will find its way to him. After Sora's memories had been restored by NaminÚ, Kairi is confronted by Axel, who hopes to use Kairi to lure Sora to him. With the help of Pluto, Kairi evades him and heads to Twilight Town, but is captured by Axel soon after. However, Sa´x takes Kairi from Axel and imprisons her and Pluto in a jail cell in the World That Never Was. She escapes her cell with the help of NaminÚ and they are saved from Sa´x by Riku, in the guise of Xehanort's Heartless. Riku gives her a Keyblade which she uses to fight off the Heartless that Sa´x summons. Kairi and Riku are reunited with Sora, and along with Donald, Goofy and King Mickey, the group face and defeat Xemnas. Kairi then fuses with NaminÚ and returns to Destiny Islands with Sora and Riku.