In the 20th period of the novel, the students are complaining about their lack of class time. Asuna and Yonada are the main culprits, but Yonada points out that they're not thugs. They're just trying to beat Yonada. Yonada says that he's made a pact with Yonada, which means that Yonada will have to fight one of the students in order to keep Yonada's job. He tells Yonada that if he doesn't do anything, he'll be fired as a teacher, and that he should go to the headmaster and tell him what's going on. He says that the headmaster wants him to sneak into the room where Yonada is alone. He asks Yonada to wait a while, so that he can kill the girl who's the one who attacked Yonada and the other students. He's not going to kill her, he says, because she's a "chachamaru" , and he'd rather kill her than let her get away with being a chachamaru