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.

Nozomi meets her grandfather, who wants to adopt her and take her to England. Kyō and the others decide to not ask her to stay in order to not influence her decision, until Kyō's sister Kurumi gives him a piece of her mind.

Kyō discovers that his online friend was not Yuzuha, but Kiryu Yume, and Yuzuha was acting in her stead. When Kiryu decides to cease all connections with Kyō and the others, they decide to find a way to cheer her up.