Wearing a cute and heavy dinosaur suit in the amusement park, Jung-Won attracts the attention of Eun-kyu who makes a fool at her. To revenge, she pours soda on him.
Hurried back home, Jung-won found out that her new neighbour who has just moved in is Eun-kyu's family. Because Jung-won was wearing a dinosaur suit, so Eun-kyu doesn't know that she was the person who poured soda on him. Eun-kyu loves music and is the lead singer in a band called Do Re Mi Fa So La Ti Do. As time goes on, both of them soon become a couple. But, everything starts to change when Jung-won goes to the band's practice place and meets her past, a guy named Hui-won. 10 years ago, Jung-won and Hui-won were close friends, but because of a misunderstood, Hui-won left Jung-won. Slowly one by one secrets of the past begins to open and causes the three of them begin to have conflict within each other.
Hui-won wishes to start over with Jung-won. Not accepting the fact, Eun-kyu lost his memories in a car accident. In order to help Eun-kyu awaken his heart's soul, Jung-won plans for a special performance with her friends.
Love, friendship and family fulfill all the corners of youth. The happiness and sadness of growing up jump on a piece of five lines paper.
Jang Geun-seok as Eun-kyu
Cha Ye-ryeon as Jung-won
Jung Eui Chul as Hui-won