Asakura's girlfriend of two years. She was traded for one night with Okubo as payment for Okubo to take down the Oni-baku. Instead of using Natsumi for one night, Okubo and his friends repeatedly had their way with her and took pictures of her as blackmail. She stayed with Okubo because she thought that Asakura was in danger. Upon discovering Asakura's trade, she attempted to kill herself with a broken glass bottle but was saved by Eikichi. After the Okubo arc, Natsumi and Asakura appear to have reconciled and plan to marry. She gets pregnant with Asakura's child and the two elope as her parents disapprove of their marriage.