Tenshi, Ei-chan, and Shiratori all attend Kawagoe Academy. One day, they get pulled into the orbit of former conductor Haruo. He drags them into his newly founded boys choir where they suddenly find themselves performing a song in front of an audience!

You're singing from your mouths again!
!تغنّون من أفواهكم من جديد
Ihr benutzt wieder
euren Mund zum Singen!
Están cantando con la boca.
Estáis cantando con la boca.
Vous chantez avec votre bouche.
State ancora cantando con la bocca!
Você está cantando com a boca de novo.
Опять вы поёте только ртом!