Even today, yōkai (jpn. 妖怪) are very important in Japanese culture. This can be seen particularly well in works of Japanese popular culture, such as anime and manga. The origins of various yōkai are often linked to legends, and their number and diversity in Japanese folk beliefs are extremely large. It is also not uncommon for them to be associated with religion; on the contrary, many are often closely linked with a religion’s origins. By interpreting the stories, traditional lore, and artistic representations, important links to the culture of Japan in certain periods can be deduced.
One of many yōkai is kitsune (jpn. 狐), which actually means “fox”, but in this particular context can rather be translated as “fox spirit”. These fox spirits are often known to take possession of people. This phenomenon is called kitsune-tsuki. The character for tsuki (jpn. 憑) means something along the lines of “to haunt” and is used in the context of possession. In Japanese folklore, however, there are not only foxes that take possession of people, but also tanuki (raccoon dog), for example.
In my research, various historical texts, legends, and reports on kitsune-tsuki were analyzed. Texts referring to kitsune-tsuki can already be found in Ancient Japan (4th century-12th century), for example in the extremely well-known Genji monogatari (“The Story of Prince Genji”), which was written by Murasaki Shikibu. Revenge, justice or rebirth are often at the forefront of the (traditional) stories and legends surrounding the phenomenon. In Medieval Japan (12th-16th centuries), performing arts such as nōh and kyōgen were added, which included kitsune-tsuki in their performances. In the Japanese modern age (16th century-19th century), kitsune became particularly important in the Inari-faith.
However, a visible change in the view of kitsune-tsuki as a pure folk belief occurred increasingly in the late Edo period (early 19th century). Although kitsune-tsuki as a “disease” had already existed in Ancient Japan, it was not until the late Edo period that the phenomenon was increasingly viewed from the perspective of psychiatry and thus associated with mental illness.