|Sacred World of the Kais|
|Name||Sacred World of the Kais|
|Notable Inhabitants||Kibito Kai, Old Kai, King Kai, Goku, Vegeta|
The Sacred World of the Kais is where the four Supreme Kais and the Grand Supreme Kai used to live, and possibly where every single Supreme Kai has lived. Most Kaioshins do not live here anymore, as the Western Supreme Kai and the Northern Supreme Kai are both killed by Kid Buu, whilst the Southern Supreme Kai and the Grand Supreme Kai were absorbed by Kid Buu, during Bibidi's quest to rule the galaxy.
During the time the Dragon Ball series is set, the Sacred World of the Kais is home to the (Eastern) Supreme Kai and his bodyguard Kibito, and later to Old Kai and the permanently fused form of the Supreme Kai and Kibito, Kibito Kai. The two Space Lemurs that Goku freed from the Sugaroku Dimension, Sugoro and Shusugoro, also live on the planet of the Kais during and after the Baby Saga.
The planet has several moons and flourishes with life, with plenty of fish in its streams and rivers, as shown in the Eastern Supreme Kai's flashback. It also has rocky and grassy areas, as well as icecaps, which was shown in the flashback. The planet of the Kais is incredibly sacred, literally to the point where, except in dire situations, such as the release of Majin Buu, even Grand Kai is not allowed to set foot there. The planet seems to be a very empty place for a large planet, as not many reside on it. This may be because of the planet's sacred value, or because it is very difficult to get there, as it took Goku a while to find Gohan in Other World when he was looking to see if he was dead or not.
Approximately five million years before the events of Dragon Ball Z, the Sacred World of the Kais was inhabited by all the Supreme Kais of the universe: Grand Supreme Kai, Northern Supreme Kai, Eastern Supreme Kai, Western Supreme Kai and Southern Supreme Kai. According to the Eastern Supreme Kai (who, upon the deaths of every other Supreme Kai, became the Grand Supreme Kai), all five of them were much stronger than Frieza. In a quest to rule the universe, Bibidi unleashed Kid Buu on the peaceful Supreme Kais. Western Supreme Kai and Northern Supreme Kai were the first and second Supreme Kais to be killed by Kid Buu, respectively. Southern Supreme Kai attempted to defeat the Majin, but was absorbed, transforming Kid Buu into his buff Ultra Buu form.
Ultra Buu attempted to kill Eastern Supreme Kai, but was stopped by Grand Supreme Kai, who was absorbed by Ultra Buu moments later. Afterward, Ultra Buu transformed into the childish and fat Majin Buu, disrupting his reputation as a cold and efficient killing machine.
During Kid Buu's second rampage, Kibito used Instantaneous Movement to transport himself, Supreme Kai and Gohan to the Sacred World of the Kais so that Gohan could extract the Z Sword from its resting place and train with it. Upon returning to Other World after his one-day pass to Earth had expired, Goku was able to sense Gohan and travel to the Sacred World of the Kais using Instant Transmission. During the course of Gohan's training, Goku and Gohan inadvertently released Old Kai from his imprisonment in the Z Sword. Old Kai then went on to begin a long and drawn-out ritual that would unlock potential within Gohan.
After many hours, Old Kai succeeded in awakening Gohan's dormant powers. Kibito then returned Gohan to Earth so that he could confront Super Buu. When it became apparent that Gohan would be unable to defeat Super Buu (who had then absorbed Piccolo and Gotenks), Old Kai taught Supreme Kai, Kibito and Goku how to fuse using Potara Earrings. Supreme Kai and Kibito eagerly and successfully tested this ability, fusing to become Kibito Kai. He was later appalled to discover that the Potara fusion was permanent, unlike the fusion induced by the Fusion Dance. Despite its apparent irreversibility, Goku felt that his fusing with Gohan was their only way to defeat Super Buu and returned to Earth with a pair of the Potara Earrings.
Kibito Kai and Old Kai both continued to observe the unfolding of events from the Sacred World of the Kais, using a crystal ball.
Following Kid Buu's destruction of the Earth, Goku returned to the Sacred World of the Kais, accompanied by the only surviving refugees from Earth, Dende, Vegeta, Mr. Satan and Bee. In an attempt to lure Kid Buu away from his wanton destruction of other planets and their inhabitants, Goku and Vegeta summoned up energy and raised their power levels. Kid Buu detected them, and used Instant Transmission to travel to the Sacred World of the Kais. Anticipating the imminent battle, Kibito Kai, Dende and Old Kai escaped to a faraway planet on the physical plane using Kibito Kai's Instantaneous Movement, but unintentionally neglected to bring Mr. Satan and Bee.
Goku and Vegeta proceeded to fight Kid Buu on the Sacred World of the Kais, ultimately culminating in Kid Buu's defeat by Goku and his Super Spirit Bomb however the battle largely damaged the planet much to Kibito Kai's distress.
During Baby's reign to terror, The Sacred World of the Kais is used as a safe place for Goku, to hide away from Baby. Goku's tail is regrown, afterwards going to the newly restored Planet Tuffle where Goku turns into a Golden Great Ape (and eventually a Super Saiyan 4). The planet does not hold much significance in the plot line after that, though it continues to serve as a residence for Kibito Kai. It is also where Kibito Kai and Old Kai witness the final battle between the Super Saiyan 4's, Goku and Vegeta, against Omega Shenron.