Twinkling Watermelon

Eun-gyeol and his family move into a new neighborhood. He meets a man who offers to teach him how to play the guitar, and Eun-gyeol works hard to learn it. As he deals with bullies at school, he practices playing the guitar until he is as good as the man who taught him. However, tragedy strikes, and he and his family are forced to move again.

Eun-gyeol tries his best to quit music, but it's not easy for him to do. He gets scouted to join SPINE9, an indie band in Hongdae. To make things worse, he finally gets his hands on the guitar promised by the Viva Music store owner. He is torn by which path to take and finds himself walking into a suspicious music store.

Eun-gyeol gets stuck in 1995 and doesn't know how to return to the present. What's worse is that he meets his young father, Yi-chan, who can talk and wants to start a band to impress a girl who isn't Eun-gyeol's mother. Eun-gyeol poses as Yoon Dong-jin, a musical genius, in order to try to become a member of Yi-chan's band.

Eun-gyeol encounters Se-gyeong in her teens and learns a few things about her life that don't make sense in the future. Meanwhile, Yi-chan meets Chung-ah for the first time, but she doesn't say a word. Yi-chan tries to get away from Eun-gyeol, but Eun-gyeol follows him to the Snail Guesthouse and ends up becoming Yi-chan's math tutor.

Eun-gyeol resolves to stop the accident that caused Yi-chan to become deaf and clings to him, vowing to teach him everything he needs to know. He even promises to gift him the band Yi-chan needs. However, the school festival is in one month, and the person Yi-chan is doing this for has left the country and isn't going to return.

Everyone is confused at Se-gyeong's return, especially Eun-gyeol, who sternly warns her to stay away from Yi-chan. However, it doesn't work, and Se-gyeong approaches Yi-chan with different intentions. Meanwhile, Chung-ah can only stand by and watch as she realizes she's lost her chance to tell Yi-chan how she feels.