On Your Own.

Soo-ah and Hyeon-jeong have been friends since they were children. Unlike Seon-hee, a hidden master in martial arts, and plain Soo-ah, Hyeon-jeong is pretty and a model student at school. While they want to lead an ordinary student's life, the Yeonsoo mob at school pressures them to join them. Soo-ah, Hyeon-jeong and Seon-hee get Seon-hee’s brother’s help and decide to fight them.