In Japan , kitsunetsuki was noted as a disease as early as the Heian period and remained a common diagnosis for mental illness until the early 20th century . Possession was the explanation for the abnormal behavior displayed by the afflicted individuals . In the late 19th century , Dr. Shunichi Shimamura noted that physical diseases that caused fever was often considered kitsunetsuki . The belief have lost favor , but stories of fox possession still occur , such as allegations that members of the Aum Shinrikyo cult had been possessed .