Arisu Yamabuki's late-night bedtimes were often accompanied by the soothing voice of radio host Apollo, but her broadcasts abruptly stopped one day without explanation. Now a second-year high school student, Arisu sets out to find Apollo, driven by a personal message he wants to share. As he searches, he becomes involved with the school's broadcasting club, where he meets four girls with their own aspirations of using their voices in a career.