Enjoying a peaceful life on the World of the Kai with his fellow Supreme Kais, East Supreme Kai was unaware until too late that he and the other Supreme Kai's had been targeted and marked for death by the ruthless wizard Bibidi, who was determined to wipe them out by unleashing his fearsome monster, Kid Buu, on them all.After hearing that Northern, Western and Southern Supreme Kai had been killed or absorbed by Kid Buu, Supreme Kai and Grand Supreme Kai prepared to face off against the buffed-up monster (Kid Buu had absorbed Southern Supreme Kai and transformed into what is known by fans as Buff Buu or Ultra Buu). While Ultra Buu was after Supreme Kai, Grand Supreme Kai intervened, but was absorbed by Ultra Buu. But Ultra Buu turned into an obese, childlike monster, and to his relief, Supreme Kai was spared by Majin Buu, who's evil had been reduced thanks to Grand Supreme Kai's good nature.
To avenge his friends, Supreme Kai eventually caught Bibidi off guard and destroyed the evil wizard while Majin Buu was locked up in a ball. Supreme Kai then hid the ball deep under the surface of the Planet Earth, fearing that he would be powerless to stop Majin Buu himself.
Supreme Kai then returned to the Sacred World of the Kais, aided by a new bodyguard, Kibito, to carry on with his life of peace. Due to the deaths of the other four Supreme Kais, Eastern Supreme Kai became known simply as the Supreme Kai. Although the title of Grand Supreme Kai was never officially given to him, he assumed the duties thereof.
The return of Majin Buu Edit
Several thousands of years later, Supreme Kai and Kibito traveled to Earth to find the help of Earth's greatest heroes, Goku, Gohan and Vegeta, for he had learned that Bibidi's son, Babidi, was planning to release Majin Buu once again. Supreme Kai eventually entered Babidi's ship along with the three Saiyans, but was transported back to the Earth grounds when Vegeta was a Majin.At the same time, Majin Buu was finally released once again, and Supreme Kai was one of Majin Buu's first victims, along with Dabura (Babidi's right-hand man) and Gohan, although Dabura was killed and Gohan and Supreme Kai were just left on the verge of death.Fortunately, Kibito found Supreme Kai, healed him, and then the two healed Gohan, teleporting him to the World of the Kai, where they would have him unlock the Legendary Z Sword and use it to help him defeat Majin Buu for good.
During the training, Goku, whose time on Earth had ended (he was dead, due to a fight with Perfect Cell seven years earlier) arrived on the World of the Kai, and accidentally got the Z Sword broken after throwing a block of Kacheen (the hardest metal in the Universe, according to Supreme Kai), which caused the release of Elder Kai, who claimed to be an ancestor of Supreme Kai.
Supreme Kai then witnessed Elder Kai train Gohan personally, and even saw him reveal his special Potara Earring Fusion to Goku (Gohan was having problems with the transformed Super Buu, and needed Goku's help), to whom he had given up his life. Out of curiosity, Supreme Kai tried the Potara Earrings, and accidentally fused with Kibito and formed Kibito Kai (FUNimation's dub is inconsistent and alternates between calling this fusion Kibito Kai and Kibitoshin).
A form of invisible ki blast available to most characters in the series. The Supreme Kai's takes the form of a gust of wind that was powerful enough to stop Majin Buu's advances toward him. Majin Buu however was able to send a more powerful Kiai blast back at him, sending him flying.
Supreme Kai demonstrated this ability by summoning a giant cube of Katcheen, the strongest metal in the world, for Gohan to practice the Z sword on.
Supreme Kai's Ultimate Blast in the Budokai Tenkaichi series. Supreme Kai gathers blue sparkling energy in his hands and releases a very powerful, pulsating blast.
Supreme Kai uses this technique during the match between Kibito and Gohan. It is powerful enough to hold down Gohan at his super saiyan 2 form.
- Supreme Kai is one of three main characters that has never died or appeared as dead in the duration of Dragon Ball Z the others are Mr. Satan and Kibito Kai, (though the latter is simply a fusion of Supreme Kai and Kibito). As such, he is one of the few characters to never die in Dragon Ball Z.
- The relationship between Majin Buu and Supreme Kai is similar to that of Frieza and King Kai. Both Kais seemed to be afraid of both villains, and keep talking about how powerful the villain is and that they cannot be defeated, and thoroughly enjoy the moment when it seems that that villain is finally defeated (Goku vs Frieza and Vegito vs Super Buu).
- Though Supreme Kai fused with Kibito, his voice did not change to a double voice like Vegito and Gogeta. This could possibly be similar to Piccolo's fusions, where one fusee has complete control over
- The attitude of the Supreme Kai changes as the anime presses forward. When he is first introduced, he squints his eyes at Goku and smiles in a manner that makes him seem mysterious and powerful. Just as what a supreme leader of the universe should be, he is calm and thinks rationally at critical moments. Later on, his constant surprise at the Saiyan's power and his dependence on others to protect the universe against Buu have made him seem more fearful and innocent. His level of authority is ignored by seemingly everyone but Kibito and the Nameks.