It has been a month since genius orchestra conductor Haruo Hibiki was unceremoniously dismissed from his position at the Cosmopolitan Philharmonic Orchestra. Unable to find a similar position, the eccentric Haruo gets roped into teaching music at Kawagoe Private Academy instead. It is here that he receives an ultimatum: if he can put together a boys' choir at the school and win the annual competition, he can return to his former job.

Desperate to return to the limelight, Haruo searches the entire school for suitable voices for the choir. Unfortunately, his inability to communicate normally puts him at odds with almost everyone he encounters—including Tenshi Dei, a boy who loves to sing but cannot do so in front of others. With only a year to complete this lofty goal, Haruo will need to learn how to get along with the boys he can manage to recruit while also supporting their growth into a formidable choir.

Kawagoe Boys Sing was set to be released on DVD and Blu-ray in four volumes from January 26, 2024, to April 26, 2024. However, the production was canceled, and everyone who had pre-ordered at least one volume received a special Blu-ray disc containing all 12 episodes.

The series was adapted into a stage play that premiered in June 2024.