From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
The Hyoga School (FUNimation "Phantom-Fang School") is a martial arts school.
The Hyoga School appeared in "Goku vs. Sky Dragon". The school was located in King Wonton's town and led by the evil Sky Dragon and his brother, Rising Dragon. They were enemies of Chin Taiken and his Chin School, and recruited students in town by force to join their school. The Hyoga School eventually reformed when Son Goku, who represented the Chin-Star School, defeated Sky Dragon in King Wonton's Royal Match. Sky Dragon and Rising Dragon then joined the Chin School.