From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
The Chin School (FUNimation "Chin-Star School") is a martial arts school.
The Chin School appeared in "Goku vs. Sky Dragon". Son Goku met Chin Taiken, the leader of the school, as he looked for a strong fighter to match his skills against during his worldwide training for the 22nd Tenkaichi Tournament. Goku and Chin Taiken fought against each other, but Chin Taiken was in bad health and could not fight for too long.
Chin Shoken, Chin Taiken's son, wanted to fight in King Wonton's Royal Match, but Chin Taiken let Goku take his place instead to fight against the merciless Sky Dragon. Chin Shoken then drugged Goku's food with laxatives and Goku had stomach pains during his match against Sky Dragon. After awhile, Goku finally used the Phantom Star technique against Sky Dragon and defeated him, thus winning the fight for the Chin-Star School. After Goku defeated Sky Dragon at King Wonton's Royal Match, the Hyoga School and the Chin School put the past behind them as Sky Dragon and the other members of the Hyoga School started anew under Chin Taiken as members of the Chin School.