The six members of the Japanese entertainment unit Strawberry Prince—Rinu, Root, Colon, Satomi, Jel, and Nanamori—spend one summer together as students at Ichigagaoka Academy. Though they are scattered individuals when they first meet, they gradually unite for a specific purpose, forming the group SutoPuri and beginning their activities as an entertainment unit. The story follows their daily lives as they gather at a café, enjoy lively conversations, and head to the sea to make the most of their summer vacation. After forming a band, the six boys make a certain promise that becomes the driving force of the narrative, depicting the bonds of friendship and shared passion for music that lead to the group's creation. The film serves as an origin story, showing how these six stars came together before their rise to legendary status in the Japanese music industry.