Im Hyung-joon

The story follows a turf war that grows between a local gang that runs Garibong-dong in Guro District, Seoul and the Heuksapa gang from Yanbian, China; the police are called in to attempt to bring peace to the neighborhood. (Wikipedia)

When Jo Kang Ja learns that her daughter is being intimidated by some classmates, she decides to enroll in high school as an undercover student to teach the bullies a lesson. (imdb)