Falsely accused of violence in high school, adult Kang Bok Soo returns as a student to get revenge on his first love and classmate who caused his expulsion. He gets caught up in the changed school's dynamics.

When Kang Bok Soo was a high school student, he was falsely accused of committing violence and kicked out of school. This was caused by his first love Son Soo-Jeong and a male student Oh Se Ho. Kang Bok Soo is a now an adult, but his life has not gone smoothly. To get revenge on Son Soo-Jeong and Oh Se Ho, he returns to the same high school as a student. The environment at the school has changed and Kang Bok Soo gets involved in unexpected cases.