|Voice Actor (jp)||Kana Hanazawa|
Ritsu Kawai (河合 律 Kawai Ritsu) is a 2nd year high school student who came to live at the Kawai Complex after her mother went abroad to work. Her grandfather is the brother of the manager of the dorm where both she and Kazunari Usa are currently staying at. The manager also considers Ritsu as her relative. When the manager isn't at home, Ritsu is trusted with looking after the dorm. She also keeps multiple weapons around the house and she doesn't hesitate to use them if one of the guys crosses into the girls side of the house.
Ritsu is a beautiful teenage girl with short brown hair and violet eyes. In school, she is seen wearing her school uniform, while on days off she is usually in shorts, and a t-shirt. She can also be seen wearing various costumes.
Ritsu is a seemingly anti-social girl who is actually very shy around others. In addition, she also likes to read books, to the point of her becoming unaware of her surroundings despite the place. when she was questioned if books are her friends, she said yes, which implies that she doesn't actually have real friends. She also states she'd rather be alone than interacting with friends who don't really want to be friends with her. However, she also cares a lot for the members at the dorms and would stand up for them when others are taking advantage of them. In addition, anytime she feels offended by any of the dorm members, she threatens them by saying that she would double or triple their rents.
The books affect her to such an extent that at times even her mood depends on the type of book she is perusing.
Before moving to the dorms, Ritsu and her mother used to live by themselves very peacefully. She later came to live at the dorms after her mother had to go abroad to work.
Ritsu shows some signs of liking Kazunari Usa, although she is not very open about it and furiously denies it whenever the other residents bring this subject up. Her feelings begin to change as the anime and mostly the manga progresses. It is suggested that she feels slightly jealous of the girls who are friendly around Usa. As of chapter 72 of the manga, she shows more of her affection for him when talking to other residents. Usa asks Ritsu on date in chapter 77 and they truly expressed their feelings in chapter 78.
- The name Ritsu means "rhythm" and "law".
- Ritsu's surname Kawai means "river" (河) (kawa) and "to fit" (合) (i).
- The Kawai Complex originally belonged to her grandfather (Sumiko Kawai's brother), but the official owner is Mrs. Kawai (Ritsu's mother) while Sumiko is just managing it for her as Mrs. Kawai is currently working in America.
- Ritsu's favorite genre is old literature.
- Ritsu's room is the furthest back in the dorms.
- Ritsu and Mayumi Nishikino are both similar to each other, but they are different:
- They are both afraid of centipedes.
- While Mayumi loves watching horror movies, Ritsu hates watching horror movies.
- Ritsu secretly has a fetish for old fashioned Japanese wear.
- Ritsu has a lot of books in her room.
- Chinatsu calls Ritsu "Loner-senpai".
- Ritsu doesn't like talking about books. However, she enjoys making recommendations and sharing opinions about the books with people who relate.
- Ritsu's parents are divorced.