Kaori Izumi

Kaori fights bare-handed and is a classmate of Rino and Ayumu. There are many strong hints that she is a lesbian as she has a crush on Kanade and resents Rino because of her close relationship with her. She has two brothers and one sister, which is why she does not live in the Gokujou dorms like the other members of the student council. She has been seen out on the streets early in the morning walking to the school, while the rest of them are already in the dining room eating breakfast, indicating that she doesn't live in the dorm rooms with the rest of the Best Student Council.

This is only clearly made known to the rest when a series of events cause them to stumble upon her house and see Kaori's siblings. [Wikipedia]