The Princess of Heart
Kairi is the best friend of Sora and Riku. She arrived at Destiny Island a few years before. She is the seventh princess. She is a strong independant young woman who is willing to help out her friends no matter what happens.
She is captured within Kingdom Hearts where her heart is missing. However, her heart is safely protected by Sora. She is not mentioned much in Chain of Memories except that Sora knows that he did something. In Kingdom Hearts II, she is left still waiting for Sora to return. She unexpectedly falls in Twilight Town causing her to have a bunch of events leading her to finding Sora.