The episode begins at Kawagoe Private School, where Haruo Hibiki struggles to get the choir to sing. Two new members, the identical twins Kou and Shin, are introduced. They are known for their constant bickering and only join the choir to earn music points for school. Their mother is called in by the principal to discuss their academic performance and the possibility of them not advancing to the next grade. The principal suggests that participating in the choir would be the best way to earn the required points.

Haruo is initially skeptical that the twins are only joining for the points, but changes his mind when he realizes their identical vocal cords could be an advantage. The twins resist but are persuaded to participate when they realize they would otherwise have to repeat a grade. During their first rehearsal, they sing a duet that impresses Haruo—not because of its quality, but because of their lack of enthusiasm, which he considers ideal.

Haruo then introduces a new competition in the choir: the "How Little Enthusiasm Can You Show" contest. The choir members are surprised, as they generally believe enthusiasm is a good thing. Haruo explains that too much enthusiasm can negatively affect their singing and points out that their enthusiasm shows in their shoulders, which should remain relaxed while singing.

The episode culminates in a choir performance during a school tour. Despite initial nervousness, they manage to perform well, impressing both the audience and the principal. Haruo praises the choir for hiding their enthusiasm during the performance and highlights the twins as the best examples.

The episode ends with the choir members finally understanding Haruo’s unconventional teaching methods, even if they still find them confusing. They look forward to the next challenge, as they now feel slightly more in sync with their eccentric teacher.