The Kai Planet is a fictional planet from Dragonball Z and Dragonball GT. It is home to the Supreme Kai, the deity that reigns over the eastern cluster of galaxies, which includes the galaxy where most of Dragonball's action takes place. Besides the Supreme Kai, his loyal follower Kibito also lives there.
 Plot involvement
It was first introduced when the Supreme Kai and Kibito transported a badly wounded Gohan to it, with the hopes that the young Saiyan would prove strong enough to pull out the legendary Z-Sword. Ultimately, this planet would be the battlescene for the final clash with Majin Buu, a fight which caused great damage to the planet. It later appears again in Dragonball GT, though only sporadically.