This drama is about a man who used to be a loner during his high school days and how he, in an attempt to revive his first love who passed away, goes back in time to when he was 18 years old. Kyung Hwi (Min Ho) was bullied when he was high school student. At that time, he liked Na Bi (Lee Yoo Bi). She was his first love, but she died. Now Kyung Hwi is a resident in orthopedics. To save Na Bi, Kyung Hwi travels back in time to when he was 18 years old.