Bilgu (1997)

The arrival of a beautiful, young teacher throws a co-ed highschool into chaos. Several cliques try to woo the teacher over to favor them, but Bil-gu, the leader of a gang called the Sharks, falls in love with her. His former girlfriend and leader of an all girl gang, sees Bil-gu and the teacher together. In a fit of jealousy, she reports their activities resulting in the teacher being fired and Bil-gu being expelled