Late at night alone in bed, your voice is the only thing that saves me. Arisu Yamabuki, the heiress of a rich family who strives for perfection in everything, is looking for that “one more percent” she needs to achieve 100% perfection. And that was Apollo, the radio announcer of “Mayonaka Heart Tune” that he heard every night. However, at the end of her middle school semester, the mysterious radio broadcaster suddenly stopped broadcasting without notice. Entering her second year of high school, Arisu decided to transfer to Kaedehayashi High School, which had just changed from an all-girls school to a co-ed school, to look for Apollo. The only clue he had was a voice he would never forget. One day, he is captivated by a familiar voice and it leads him to the front of the school's broadcast club, where four girls with different dreams gather. Rikka Inohana dreams of becoming a singer. Nene Himekawa wants to be a seiyu. Iko Kirino, who works as a VTuber. Shinobu Uzuki dreams of becoming a broadcaster. Each girl reminds Arisu of Apollo. Arisu is determined to help these four girls realize their dreams regarding "voice", as well as finding out the mystery of Apollo's true identity.