Tenshi Dei, known as "Danbocchi," is a former choir member whose crippling fear of singing in front of others drove him into isolation. He confined his singing passion to the solitude of his home, a retreat that cemented his reclusive nickname. His quiet existence shatters when Haruo Hibiki, a disgraced orchestra conductor desperate for redemption, uncovers Tenshi's hidden vocal talent. Hibiki, needing to win a national boys' choir competition to regain his professional standing, forcibly recruits the reluctant Tenshi into the newly formed Kawagoe School Boys Choir Club, leveraging his own forceful persistence. Thrust into the demanding world of choir performance, Tenshi grapples with Hibiki's abrasive methods and the challenge of collaborating with others. Despite persistent anxiety and initial struggles, rigorous training and repeated exposure begin to chip away at his fear. Through the shared mission of winning the national competition, Tenshi finds gradual confidence within the group, shifting from solitary practice to collective artistic pursuit.