The novel opens with a description of a sexual relationship between a young man and his older sister. The young man, who is named Nemo, is in love with his younger sister, Nonoka, whom he calls "my sister." The two of them have been together for three days, during which time the young man's mother and father have been absent from the house. When they return home, they find that the door to the house is locked and the door is creaky with the sound of the creak of the door's hinges. When Nonoka asks why she is not allowed to clean her room while she is in it, the young woman replies that she has to cook for her father and her father's upcoming trip to China. The girl asks if she can eat some food, and Nemo replies that he thought he could cook some decent food. When the girl asks why the food is burnt, he replies that it is because Nonoka always cooks. When she asks why, he says that she always cooks for him, and that he has no choice but to do so. He asks her to help him clean his room, and she agrees. She asks him to get rid of his sailor's uniform from when he was in school, and he agrees. He tells her that he is sure that she will not need it any more, as she is getting fatter. She tells him that if the uniform does not fit, she will have to kneel and apologize to him. He says that if she does not, he will put it on, and prove her wrong. She says that he will listen to what she says, and when she laughs, he laughs and says that it looks immoral and sex