The narrator is a young man who lives with his younger sister in a Tokyo apartment. When the narrator’s sister decides to marry her boyfriend, a man named Noboru Watanabe, the narrator immediately disapproves. One day, while eating spaghetti at a restaurant, the narrator’s sister tells him he should grow up: He cannot continue avoiding serious relationships. The narrator, annoyed, goes on a date with a girl who is not his girlfriend and drinks heavily. He reflects on his relationship with his sister and how it began to deteriorate when she started dating her fiancé, whom he disliked from the very beginning. He eventually meets him on a few occasions, has dinner with his family, and even admits that he is not a bad guy, but he still does not like him.

Shortly after the “spaghetti argument,” the narrator’s sister has Noboru over for dinner at their apartment and the three eat together. Noboru, an engineer, fixes the narrator’s stereo set. The narrator drinks heavily during dinner and makes jokes, and his sister chides him again for not taking anything seriously. After dinner, the narrator goes out, sleeps with a girl he meets at a bar, and comes home drunk after midnight.