Located in Thrive Central's 7th Ward, Tensho School highlights extracurricular activities, including an annual autumn singing contest participated in by all clubs. Saku Otonomiya, a recent transfer student, had to postpone the start of his school year due to his sister's hospitalization. As he adapts to his new life, he strives to balance caring for his sister and working part-time while struggling to find the time to join a school club. In preparation for the singing contest, the school's singing club desires to use Sousuke Kagura's "Cloudy Days," but Kagura hesitates to grant his permission. He is convinced that the song necessitates a three-octave range, one that only a VOCALOID could accomplish. Thus, he consents to the club's request only if they can discover someone with that vocal capability to perform it fittingly. While musing over his next song, Kagura happens upon Otonomiya singing "Cloudy Days" faultlessly. Kagura asks Otonomiya to join forces with him for the competition. Simultaneously, the singing club persistently encourages Otonomiya to join so they can utilize Kagura's song. As the contest draws nearer, Otonomiya grapples with his hesitation and must elect which partnership to form.