Second-year high school student Aoi Aioi is an aspiring musician. Her older sister Akane's ex-boyfriend Shinnosuke Kanomura is a struggling guitarist. Aoi and Akane's parents passed away in an accident 13 years ago, and Akane gave up her ambition of going to Tokyo with Shinnosuke to take care of Aoi. Since then, Aoi has felt indebted to her older sister. One day, she is invited to perform at a music festival as a session musician by a famous en singer named Dankichi. At the same time, Shinnosuke returns to Aoi and Akane's town after a long time away. Then, Shinno mysteriously appears- who is actually Shinnosuke from 13 years ago after traveling from the past to the present-and Aoi falls in love for the first time.—Kamiiyaz

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.—Sitges Film Festival

The storyline revolves around three people, Shinnosuke, Akane and Aoi. Akane and Shinoo as high school teens, fell in love with each other but had to sacrifice their love because of their own priorities. Aoi is Akane's little sister who would come with Akane to Shinoo and his band rehearsals and as a kid started idolizing Shinoo . After Akane and Shinoo fell apart, Shinoo moved out of his town as an aspiring guitarist in hope of achieving his dream of being a part of a popular band and Akane stayed in her town to look after Aoi after her parent's death. After many years Akane and Shinoo finally meet again when grown up Shinnosuke come to his old town to perform as a guitarist in some band. Meanwhile, Aoi, now a teen found her passion in playing the bass and one day while rehearsaling in an old place (where Shinoo and his band used to do their rehersals) stumbled upon Shinoo, but not the grown up Shinoo, a teenage Shinoo. Aoi soon started to develop feelings for the teen Shinoo. The rest of the story explores the different relationship dynamics between these three people and how they overcome their own regrets. The teen Shinoo (spirit) act as a catalyst who helps each of them with their issues.