Kyō Nukui is a shut-in high schooler with a love for music, often posting his music online under the fake name of HibikiP. One day, an anonymous sender wants to meet him at a park, to which Kyō agrees, thinking it to be a middle-aged man interested in discussing music like him. However, the anonymous sender turns out to be three elementary school girls Jūn Goto, Nozomi Momijidani, and Sora Kaneshiro, who request that he play his music with their band in an upcoming concert. They perform first for him, and despite being highly impressed with their musical skills and vintage instruments, is still unsure about his decision.
Aoi Koga
Sora "Kuu" Kaneshiro (Main Character) (voice)
Yurika Endo
Nozomi "Zomi" Momijidani (Main Character) (voice)
Yuko Ono
Jun "Jun-tan" Gotou (Main Character) (voice)
Yuki Inoue
Kyou Nukui (Main Character) (voice)
Kana Hanazawa
Koume Ogi (voice)
Kanae Itou
Sakura Toriumi (voice)
Rina Hidaka
Kurumi Nukui (voice)
Toru Okawa
Masayoshi Sawatari (voice)
Yuka Iguchi
Yuzuha Aigae (voice)