Shihara’s sister-in-law, who is married to Shihara’s younger brother, is a direct and determined young woman who wears a lot of makeup. Shihara hates her because she has convinced his brother and parents not to give him money whenever he asks for it. When Shihara agrees to a fake relationship with Keiko, he moves into her apartment and skips out on paying rent on his previous place; his sister-in-law repays Shihara’s debt to his roommate, tracks Shihara to Keiko’s apartment, and demands that Shihara pay her back. When Shihara claims that he and Keiko are planning to get married, the sister-in-law tells them that they need to get better jobs and lectures them about needing money and health insurance. Unexpectedly, Keiko thinks the sister-in-law’s interference is rather kind. Later, when Keiko is trying to find some meaning for her life outside the convenience store, she asks the sister-in-law whether she should have children; when the sister-in-law tells Keiko in no uncertain terms that Keiko and Shihara should not pass on their genes, Keiko is relieved and grateful. The sister-in-law’s horror at the idea of Keiko and Shihara reproducing may accidentally help Keiko reject Shihara’s influence and return to convenience-store work.