Onmyouji and Shikigami go hand-in-hand, and not just because they’re both hard to pronounce. Although Onmyouji by and large, practiced a form of divination arts, many believed that the truly powerful ones were capable of controlling spirits and demons.
Shikigami (she-ki-ga-mi) 式神, are such spirits that Onmyouji could have do their bidding. Depending on how good the practitioner was, shikigami could either have the form of human or animal and could even possess others to be controlled by the Onmyouji.
It’s said that Abe no Seimei had the Twelve Heavenly Generals under his command, but their faces were so frightening, they scared his wife, so Abe had them stay under the Ichijo Modoribashi bridge.
Inugami (ee-nu-ga-mi) 犬神, are a form of Shikigami, that usually takes the form of a dog. But the spirit is such a high form of shikigami, that those who possess it, run the risk of losing control and being controlled by it instead.
The Inugami is also a form of kodoku 蠱毒, an insect or animal spirit used with the intention to curse a person. Those who control the Inugami are called Inugami-mochi. The spirit is created through the hands of man, first burying a live dog in the ground, leaving only its head outside. Then putting food out of its reach, starving it to death, and just before it draws its last breath, beheading him from the back. The head is then buried in a populated area, where it is trampled. After the head is dug out and honored as a cursed object, the Inugami is evoked.
Inugami are tsuki-mono, spirits capable of possession. There are families known as Inugami-suji who inherit the ability of controlling Inugami through the bloodline. The spirit increases as the number of girls born in the family grow and when the daughter marries, the spirit follows along into her husband’s home. Honoring the Inugami brings wealth and fortune to the family, but if it grow resentful for whatever reason, the suji will experience chaos and calamity. And once a family has become Inugami-suji, there is no escaping their fate unless the bloodline dies out.
Those who control the Inugami can also induce them to possess enemies. A person (women are usually easier to possess than men) possessed will show signs of delusion and wild mood swings and will act strangely, such as going down on all fours like a dog. In the Tokushima district, there is said to be another Inugami who can invade a person through their fingertips and reach vulnerable areas through the bloodstream, frequently causing unexplainable high fevers.