In the year 2023, Joon-hee continues to miss her boyfriend Yeon-joon who died a year ago. She somehow travels back in time to 1998 and wakes up in the body of a different person, 18-year-old Min-ju, and meets Si-heon, who bears an uncanny resemblance to her deceased boyfriend. In-gyu, Si-heon's best friend, has had a longtime crush on Min-ju.
