A high school student spends the summer in a small mountain town where humans and ayakashi have always coexisted. She has the nagging sense she has been here before — that the people she meets, including the ayakashi Giou, Shinonome, Shu, Takatora, and Chihaya, mean something to her she cannot name. Then a new, hostile ayakashi arrives. Strange phenomena follow. The full moon is drawing near, and she is being pushed toward a memory she has been keeping herself from facing.