Tensho School is situated in the 7th Ward of Thrive Central, a place that prioritizes extracurricular activities, with all clubs taking part in an annual fall singing contest. Transfer student Saku Otonomiya is forced to postpone the start of his school year because of his older sister's hospitalization, leaving him struggling to adjust to his busy new life. Juggling a part-time job and caring for his sister, he finds it hard to carve out time to join a school club. As the school's singing club prepares for the upcoming contest, they wish to use Sousuke Kagura's song "Cloudy Days," but Kagura is hesitant to give his permission. The song demands a three-octave vocal range, and he believes only a VOCALOID can meet those standards. He agrees to let the club use his song on the condition that they find someone with that specific vocal range to sing it properly. While Kagura is struggling to compose his next song, he happens to hear Otonomiya singing "Cloudy Days" flawlessly. He invites Otonomiya to form a unit with him for the competition. Meanwhile, the singing club attempts to persuade him to join so they can utilize Kagura's song. As the contest draws nearer, Otonomiya must confront his uncertainty and decide whom to team up with.