Upon being sent to live with relatives in the countryside due to an illness, an emotionally distant adolescent girl becomes obsessed with an abandoned mansion and infatuated with a girl who lives there – a girl who may or may not be real.

After her parents divorced, Shima Sumitomo lived with her mother. She felt uncomfortable living with her stepfather and she was unable to hang out with people at her high school. Shima Sumitomo decides to move to Hokkaido where her father lives. At her new high school in Hokkaido, she meets classmate Gen Tatebayashi and Wao Sakurai. They are the two most popular boys at her school. A principle of her school is that “Gen and Wao are for everyone.” If anyone breaks the rule, that person will be ostracized. Even so, Shima Sumitomo gets closer to Gen and Wao.