Via Pink Tentacle’s Edo Period Monster Paintings:
An Inugami (lit. “dog god”) is a familiar spirit that looks like a dog and acts as a protective guardian. Inugami are extremely powerful and loyal, and they are known to carry out acts of revenge on behalf of their “owners.” They can also exist independently, and under some circumstances they may turn against their owners. Inugami also have the ability to possess humans.
… In the Oki Islands, the inugami takes on the function that the kitsune (fox) holds in many other regions of Japan. It is believed that an inugami-mochi will be blessed with great fortune and success, and that favors granted by them will be returned with interest. However, in exchange the inugami-mochi are shunned by other people, and find it hard to get married; they must also be careful not to offend their inugami lest they receive its wrath, as unlike the kitsune, an inugami does not merely follow its master’s wishes, but also acts on its own impulses.
Many small villages in Japan are considered to have at least one old lady with the power of the inugami-mochi.
Gilgablog 