During the sex training session at the university, a girl named Mioka tells her friend, Touma, that she's been having sex with another girl named nagisa. Mioka says that this is why she hates girls, because she has sex with a girl who isn't "a good girl" . The girl tells Mioka that she and Touma are going to have sex, and Mioka wants to know what's going on. She asks Touma if he'd like to try a new sex toy that he's seen before. Touma says no, but Mioka insists that she wants to try it with Touma. The two of them try to get Mioka to slap Touma's butt, but she doesn't want to press the button, so Mioka grabs the girl's penis and squeezes it with her fingers. The sex toy is so small that Mioka can't get Touma to do the same thing with her, so they have to do it both at once, but the girl is so excited that she forgets to show Mioka the sex toy.