尾上 沙希

She is the eldest daughter of the Onoe family and is an active schoolgirl who attends an advanced school in Tokyo. She is a member of the swimming club and is a promising prospect for the club.

She is good-looking and popular among both boys and girls at the school, but she has never been in a relationship with the opposite sex and is a virgin. She is also the chairperson of her class.

She is an athletic girl with a very competitive side who puts her hands before her mouth. On the other hand, she is surprisingly girlish and hates men.

She is a childhood friend of the main character, and as a child, she was fond of him. Saki, who is a manly girl, used to carry him around as her henchman.

She seems to have an aversion to the protagonist, who is a housemate whom his mother has accepted on her own accord, despite their reunion after 10 years, She is always acting in an unfriendly manner.