Suuna, a high school student with a communication disorder and a total gloomy loner, starts her dormitory life today. As she enters her room with nervousness, there she finds... her roommate, Ruka, flirting with another girl! Ruka claims she's in trouble if she doesn't have a "sex friend" because she craves human warmth. Suuna, who doesn't want Ruka to bring strangers into their room, impulsively proposes a "Semi-Friend Contract"...?