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.

Second year high school student Kodaka Hasegawa has transferred to his new school about a month ago, but he still hasn’t made any friends. Kodaka Hasegawa was born from a Japanese father and a British mother. Because of his appearance, people think Kodaka Hasegawa is a troubled kid. One day, Kodaka Hasegawa sees classmate Yozora Mikazuki pleasantly talking to herself. Kodaka Hasegawa talks with her about how to make friends. To make friends, Yozora Mikazuki decides to form the Neighbor’s Club and forces Kodaka to enroll in the club.