The original My Boss, My Hero hilarity came from the irony of a gangster in his 30s going to high school and attempting to get a diploma without revealing his criminal identity. The gangster, Kye Du-sik, tries to get along with his much younger classmates and ends up solving problems at the school.
In the sequel My Boss, My Hero 2, Kye has graduated and entered college. He is dispatched to a high school to work as a student teacher for four weeks.
The problems in high school are worse than the original. Kyu witnesses one especially corrupt teacher forge the scholastic documents of privileged students whose fathers are high-ranking politicians, and have a sexual relationship with a pupil.