A CODA (child of deaf adult) student Eun Gyeol has hearing-impaired parents, but he has a gift for music. He is a model student by day and plays the guitar in a band at night. One day, he visits a mysterious musical instruments store and travels to a strange place. There, Eun Gyeol meets Lee Chan, Se Kyung, and Cheong A. They form a band called “Watermelon Sugar.” Meanwhile, Lee Chan has a crush on Se Kyung, who is known as the “Cello Goddess” of Seowon Arts High School, and tries to win her heart.