Note:I do not in any way approve of cruelty to animals. PLEASE DO NOT DO IT for real.
Inugami, or literally "dog-god" is a kind of spirit that can possess a human, and is a type of kodoku(1*) The belief in this spirit was still strong until recent years and was widespread particularly in the western part of Japan.
Those who can create and command Inugami is called "Inugami-tsukai" (literally, dog-god user). Inugami-tsukai creates an Inugami by the following method; first, you take a live dog and bury it in the ground up to its neck. Then you put some food in front of the dog but just beyond its reach, so that the dog is able to see the food but is not able to eat it. You then let the dog starve and when it is near to death and its desire for food is at its strongest, the Inugami-tsukai must go behind the dog and cut off its head. The dog's head is then buried undeground in the middle of a cross-road; this is to get as many people walk over it as possible in order to intensify its grudge. Finally the head is dug up and enshrined. Now a powerful inugami is born (2*).
Inugami can be commanded to possess a person. Those who are easily possessed by Inugami are the ones who are emotionally unstable. The possessed may act and say odd things, complain of pains in the chest and limbs, and sometimes walk on all fours and even bark like a dog.
In order to exorcise an Inugami you need either eat a charred beast, or ask a Yamabushi (3*)to perform a special ritual (involving use of fire and incantation) for you.
The size of Inugami is about the same as a large rat. Some say it is covered with spots and is blind. It is usually invisible to ordinary humans.
Inugami-suji "The Dog-God Bloodline"
The family which is possessed by an inugami is described as "Inugami-suji", meaning "dog-god bloodline." They are said to be the descendants of the shamans and sorcerers who originally created Inugami.
If the family worships it the Inugami bestows prosperity on it; on the other hand if the spirit is treated poorly it will bring calamity to the house.
In Inugami-suji household, a new Inugami is created every time a girl is born. When the girl marries, she is said to take her Inugami with her, thus making the new household an Inugami-suji too. For this reason normally marrying to an Inugami-suji was the thing to be avoided by common people. In few areas of Japan, some people still check the bloodline of the bride before marriage to make sure that she is not from an Inugami-suji.
1*Kodoku - a black magic that uses living animals; will be explained more in detail on this blog in the near future.
2*This is the most well-known method. A source says when the dog's head is cut off it should fly and bite the food in front of it.
3* Yamabushi - lieterally meaning "one who lies in the mountain" Yamabushi is a Japanese ascetic and is a practitioner of shugendo, a syncretic religion mixing Buddhist and Shinto elements. (wikipedia).
*The picture shows Inugami ( from wikipedia japan)