King Yemma is a notable character in Dragon Ball Z, but despite his role over the afterlife, he’s actually a minor figure in the overall story. He’s based on the Buddhist deity King Yama, who was originally derived from Hinduism. In Japanese, his name is King Enma. In the English dub, it was changed to King Yemma, which arguably makes it even more distorted. His role closely follows religious tradition, as he judges the souls of the recently deceased.

Goku meets him soon after dying, when Kami escorts him so arrangements can be made for him to meet King Kai and begin his training. This leads to a very hilarious scene where Kami accidentally insults King Yemma and gets threatened with a terrible afterlife.

One thing that always confused me about the logic in Dragon Ball is that only characters like Goku and his friends are allowed to keep their physical bodies, while everyone else appears as a cloudy soul. Yet King Yemma talks and behaves as if Raditz received the same treatment. Then in the anime, even the villains are shown with their bodies in the afterlife, which creates a strange inconsistency.

He doesn’t really do much again until the Majin Buu Saga, when he decides to preemptively save Vegeta’s body in the afterlife. He figures he may need to send him back to Earth as a last-resort backup plan in case everyone else dies.

He later watches Goku defeat Kid Buu and destroy him. Afterward, Goku asks for Kid Buu to be reincarnated and King Yemma makes sure the pink alien demon is eventually reborn as a human boy named Uub.