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!

Open your mouth real wide.
افتح فمك واسعاً، مُستعدّ؟
Schön laut, ja? Also …
Abre bien la boca.
Abre bien la boca.
Mets-y du tien, allez.
Открой ротик пошире.