Nogitsune (wild foxes) will possess a person, but not high-class foxes -- and their victim will blurt out such things as:
" I am God of Inari" -- or "Let me eat azuki-meshi."
When possessed by a high-class fox, however, the victim will appear like a true sick person. So the patient can be put under the care of a doctor. The doctor, however, cannot tell whether his patient is possessed by some phantom, or mentally deranged.
"The Kitsune-tsuki patient will look sometimes mentally deranged; and other times will appear to be sane and sound. The condition of the Kitsune-tsuki patient is different during the day. At night, he will find it hard to go to sleep -- or sometimes will try to commit suicide in desperation.
"The patient has a strange habit. He will not allow any person to come near him when taking his meals and he is particular about what he eats, and likes to keep company with persons inferior to himself in intellect.
"He will avert his eyes from other people when sitting opposite them. He will invariably turn his face aside or drop his eyes, putting both his hands on his knees and shrugging his shoulders.
The cause of Kitsune-tsuki may be attributed to:
1. Impediments in mood.
2. Impediments in the Organs of perception.
3. Impediments in the function of association.
4. Impediments in consciousness.
5. Infection of mental derangement.
Dr. Shinshi Kadowaki, "A New Study of Kitsune-tsuki Disease"
Medical department of Tokyo Imperial Univeristy