Ritsu is a 2nd year high school student who lives in the same dorm with Usa. She is a seemingly shy girl who likes to read books. Her grandfather is brother to landlady of their dorm who views Ritsu as her relative. She is trusted with looking after the dorm when landlady takes a leave. She keeps multiple weapons around the house and doesn't hesitate to use them if one of the guys crosses into girls side of the house.