After Kiyono joins the society, the girls become aware of her habit of teasing what's under her skirt in front of boys. She flips up Yako's skirt and makes fun of the underwear, only to show some embarrassment when she flips hers back. The girls are surprised when Kiyono takes off her underwear before leaving. The next day, a moral exam is held and Kiyono is told off for wearing makeup. In the meeting later that day, Nayu brings a deconstructed bra, but Kiyono shows disinterest. She then insults Mizuno, particularly about her femininity and bra choice, and shows everyone catalogues of more kinky underwear. Kiyono argues with Nayu over looks vs comfort, but feels some embarrassment when the topic of who she loves is brought up.

As the Underwear Society make preparations for the drama club, they are asked to participate in the performance. After school, Nayu runs into Kiyono, who had heard about Keigo's job offer. The next day, Nayu takes on some extra work whilst Kiyono tells Hiroki about Nayu's apparent transfer. He confronts Nayu about this, who asks him to stay quiet until after the festival. On the day of the festival, Tsukamoto confronts Mizuno and Nayu about the society's appearance in the magazine. She asks the play to be cancelled, but Mizuno stands up to her and tells her to hold her judgement until after she's seen their work. However, during her inspection, Nayu's old elementary school teacher comes in a berates Nayu. Thankfully, both the society members and Tsukamoto stand up to him, the latter of which allows the play to take place. After a successful performance, Nayu tells Yako and Haruka that she's transferring as Keigo tells Mizuno the same thing.