East Kaoshin or Supreme Kai (Funimation dub) is the ruler of the East Quadrant of the universe. After the other Kaoshin were killed or being absorbed, and Majin Boo was sealed in his prison, he has been making sure that he has stayed sealed.
Majin Boo Saga
East Kaioshin lives on a small planet far away from Earth. He came to Earth to warn the Z-fighters that a wizard called Babidi was going to unleash a monster called Majin Boo. He has a bodyguard called Kibito. He took the injured Son Gohan back to his planet to help him get stronger so he could defeat Boo. He shows Gohan the Z-Sword and then, Gohan pulls it out of the rock it was in.