I reunited with my younger childhood friend, whom I had always thought was a boy, only to discover she was actually a girl who had become a genius beautiful violinist. ~As a result of saving her from her slump, she confessed to me during a live broadcast interview~

A university student living alone, Kishitani Tomoki. One day, he receives a message from Ichinose Rikka, a childhood friend who is much younger than him. The sudden contact from the younger childhood friend he had grown distant from was about coming to Tomoki's apartment where he lives alone. In front of Tomoki, who was restless about their reunion after so long, a beautiful girl was being harassed by delinquents. He helps the beautiful girl and tries to leave the scene, but... the beautiful girl was actually his childhood friend Ichinose Rikka. Tomoki is bewildered to find that the childhood friend he had always thought was male has become a beautiful girl. This is the story of how he saves Rikka, who has become a genius violinist in a slump, until she confesses to him during a nationwide broadcast interview.