From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Grand Kaio (大界王, Daikaiō; FUNimation "Grand Kai", Viz "Dai Kaio"; Literally meaning "Great World King") is the superior of East Kaio, North Kaio, South Kaio, and West Kaio. His superior is Grand Kaioshin.
Grand Kaio is portrayed as an aged hipster who usually wears jeans and a denim jacket and constantly listens to rock music on his boom box.
Son Goku was brought to Grand Kaio at the beginning of the Great Saiyaman Saga by North Kaio. His home was on Grand Kaio's World. He was considerably stronger than the other Kaios and was known to be the greatest fighter known. Even though he was the teacher of the greatest warriors ever known, Grand Kaio (much like North Kaio and Turtle Hermit) was more of a sweet and kind grandfatherly figure than a traditional disciplinarian. Paying no heed to respectful-but-cold formality, he lovingly treated his social inferiors as equals and doted on them as if they were his own grandchildren. In the Japanese dub, he affectionately addressed younger warriors with the suffix of "-chan" (Goku-chan, Paikuhan-chan), a term of endearment usually reserved for young children.
Although Grand Kaio did not appear in the Dragon Ball manga, a Dai Kaio (meaning Grand Kaio) was mentioned. In fact, his characterization in the Dragon Ball Z anime was suggested to the production staff by Akira Toriyama himself.
- Melchior, the swordsmith that Akira Toriyama created for Chrono Trigger, resembles Grand Kaio in his formal attire.
- Despite his position, he is not as strong as Pikkon or Goku due to having neglected his training. This is why he uses the full breadth of the rules to keep from having to teach either of them immediately at the conclusion of the Next World Tournament.