The adolescent romantic drama story set on Enoshima island in Kanagawa Prefecture. It centers around five Japanese high school students who are too young to be called adults, but who no longer think of themselves as children.

Wakana Sakai once took music lessons, but she withdrew from music after losing her mother. Konatsu Miyamoto is a positive-thinking girl who loves singing and spends time after school at the vocal music club. Sawa Okita is a spirited archery club member who dreams of becoming a horse rider. Taichi Tanaka is a chronically late badminton team member who lives with his college student sister. Win just transfered into Wakana's class after 12 years abroad in Australia. Music brings Wakana, Konatsu, Sawa and the others together into an ensemble during their last summer in high school.