After being asked to join a music agency, Setsu realized that he wanted to compose a unique improvisational piece and play it in front of as many people as possible. Setsu forms a new unit with Kaji, Arakawa, and Soichi Tanuma's little sister, Mai. The four of them record a new album that will breathe new life into the music world!! However, with his impressive abilities and Umeko's production, Setsu's older brother, Wakana, has already caused a huge sensation of his own…?!