The chapter opens with a flashback to the first sexual experience that the narrator has had. The narrator tells us that it was with Kisarazu, and that she has solved the next math problem that she is supposed to solve. The teacher, however, has already solved the first math problem, and the narrator asks the teacher if he would like to solve the next one himself. When the teacher tells him that he should try it, the narrator says that he will give it another try later on. He then tells the teacher that he is afraid that the girl will not come to class because she does not feel well. He tells the girl that he has asked her to come, but she has refused to come. He asks the girl what she does when she is not at school, and she says that she trembles when she finds him. The girl tells the narrator that she will keep the secret from her homeroom teacher, since they have a chance to discuss the next problem together. She then tells him to hurry up and leave the room. When she hears the teacher's voice, she runs to the room and trembles. She tells the boy that he must hurry up because he is busy. The boy tells her that he needs to get away from the room because the girl has given him the wrong answer to the math problem. He says that the teacher is a good teacher, but that if he does not get away, the teacher will say that he was joking about the problem. The young boy says that if the girl is not feeling well, he should not push himself to solve more problems. He also says that math problems are not word problems, but problem-based ones. He wants to know how he has to make sure that he doesn't make any noise when he is working on the problem