The Cougars scored the winning run in the sixth inning when catcher Bryce Marcouiller singled and his pinch runner Mason Masaki crossed the plate on an error.
The win enables Kaiser (10-5) to move on in the tourney and play Maui Interscholastic League champions Waiakea on Thursday at 9 am. at Les Murakami Stadium.
Kauai kept the close on the strength of excellent pitching by David Jordan Buster, who went six innings and held Kaiser to six hits. Kauai’s Andrew Renaud collected two singles to lead both teams in muilt-hits. The Red Raiders will play Kalani on Friday at 10 am in the consolation game at Central Oahu Regional Park.