Ayako Haibara is a hostile female spirit in Fatal Frame IV: Mask of the Lunar Eclipse. She was one of the many patients that suffered from Luna Sedata Syndrome. She was being treated inside of Rougetsu Hall, a sanatorium built on Rougetsu Island specifically to attend to patients of Luna Sedata Syndrome. She is also one of the patients that knew the heroines of Fatal Frame IV during their stay in Rougetsu Hall. Ayako stood out from the other patients due to her homicidal tendencies. Eventually she met her end when the disease could not be controlled and she finally bloomed.