Yoshihisa doesn’t have any relatives, but he doesn’t feel sad or lonely. While there’s nothing wrong with his personality, he finds it difficult to connect with others. Upon acceptance to the school, the school director offered him a cheap room if he helps out around the apartment. He meets the other residents: dojikko classmate Hina, the class rep Natsuki, and his teacher and self-proclaimed guardian Fumika. One day, a girl arrives carrying a letter and introduces herself as his imouto.