Kairi is a young girl from Destiny Islands. She is good friends with Riku, Daisy and Lucas. When the island is ripped apart by darkness, she is seperated fromher friends and ends up in Hollow Bastion. However, with Lucas's and Riku's help, she makes it back. She is a Princess of Heart, so she was used to open the Door to Darkness (otherwise known as Kindom Hearts).
Super Smash Bros.
Kairi pops up in Super Smash Bros. Evolution along with Riku, Lucas, and Disy. She wields the Keyblade that she has in Kindom Hearts 2. Her Final Smash is "Destiny's Call", which is similar to Peach's Smash from SSB Brawl.
Twisted Evil 2
Kairi will cameo in this possible sequel to the popular cross-over story.