When their parents died, Akane remained in her hometown to take care of her little sister, Aoi. Years later, Akane's ex-boyfriend, Shinnosuke, returns to town to perform at a music festival. At the same time as the re-encounter between the two former lovers, Aoi meets Shinnosuke's teenage self, who has traveled through time, and she falls head over heels for him. The team from the moving The Anthem of the Heart returns with a surprising story full of romance and youthful longings.