Takanashi Yumi

A student of Masaya's, she is an honest, quiet, honor student type of girl. In fact, her grades are good, and combined with her cute appearance, she is treated as a bit of an idol in the school.

However, she is unaware of this, and at home she plays the big sister to her younger sister, Shiori.

She has never been with a man and is still a virgin. Perhaps because of this, she has a strong sense of chastity and rejects Masaya as a “man,” but she is manipulated by the power of the notebook and opens her legs in front of a man.