Rei works as a professional freelance photographer. She met her fiancé, Yuu, while they were in college, where he studied anthropology and folklore. Yuu was good friends with Mafuyu Hinasaki and Kei Amakura, and the three worked together in their research of the occult and local customs. Before disappearing, Mafuyu entrusted Yuu with his sister's care should anything happen to him, and after becoming engaged, Rei and Yuu bought a house together, and took in Mafuyu's sister, Miku. Rei was never told about Miku's past, or what had happened to her brother, and the two became good friends, Miku began working under Rei as her assistant.