In the folklore of witchcraft, it isn’t unusual for a witch to a have an animal assistant, known as a familiar. Depending on the animal – and the culture – a familiar can serve multiple functions, and in certain traditions, the witch’s very powers depend on its wellbeing.
This would be the case in Japan, where the two most common familiars are foxes and snakes, with foxes being more prevalent. The fox, or Kitsune, can attach itself to an individual, or can belong to a family.
The solitary practitioner, or Kitsune-mochi, gains their familiar through offerings of food. The Kitsune-mochi then makes a formal pact, providing care in exchange for magical services.
There are several services a familiar can provide: the Kitsune can become invisible; it can retrieve desired objects; it can shape-shift, and deceive the Kitsune-mochi’s enemies. However, of all of its powers, the most dreadful is the Kitsune’s ability to posses another human.