From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Mijorin (ミゴレン, Migoren) is an alien.
Mijorin's Japanese name is a pun on the word Miigoren.
Mijorin first appeared in "Tournament Begins". He was formerly from the Northern Galaxy and had "fought off an army of evil invaders, about 7000 years ago" according to North Kaio, his trainer. Throughout the Anoyoichi Tournament, he recognized Son Goku's amazing fighting abilities.
Mijorin made a cameo appearance in Dragon Ball Z: Fusion Reborn.