The Kyuubi is the Nine Tailed Beast inside of Naruto Uzumaki. The Kyuubi is a demon and wants Naruto to use him a lot. The Kyuubi has injured the wife of its host when they where younger. Some of the Kyuubi's Chakra was taken by the Fire Temple and putinside of Sora. Sora has reached the fourth tail but not higher, but Naruto has reached farther than Sora.