Shikigami are a type of familiar used by practitioners of Onmyoudou. The term 'Shikigami' refers to servants that Onmyouji manipulated, 'shiki' meaning 'servitude', and shikigami being 'spirits who serve their practitioner'. They are the partners and guards of the practitioner, and to put it roughly, they were servants or slaves, even 'tools'.
The more skilled a practitioner is, the more precision and control they can exert over their shikigami. A high-level practitioner can even synchronize with their familiar to the point where they can feel what they do. In addition, the master's magic can't harm the shikigami.
There are 2 main types of shikigami: Servant and Man-made.
There is also sub-classes, which describe their uses.
Servant type shikigami are spirits and living beings that serve a practitioner, including humans and living spirits that can be turned into them through a contract. They possess their own unique abilities and can think on their own, for the most part. The 'tradition' of the Tsuchimikado Family was that the branch family had to serve the main family as a shikigami, in which case this meant they acted as their servant.
Shikigami which were created by putting magical energy into a ‘core’ that was the vessel, whether a paper doll or something like a sword or even a motorcycle. The 'General Onmyoudou' that the Onmyou Agency formally adopted primarily used man-made shikigami, including simple shikigami which are forged from the users energy and then manipulated directly or given orders beforehand to on them, or standard shikigami that possess an external power source and can act on its own to a degree.
There are also a class of shikigami that is high-leveled enough to be able to think and cast magic on its own.
A category of shikigami that applies to demons, spirit beasts, and other related creatures that went through special means to become a shikigami of an individual's servitude. This class also takes the place of the servant-type in the manga.
- Hokuto (Dragon)
These shikigami are made for various, non-specialized uses.
These shikigami could be used to move the practitioner or transport objects.
detection-types that could investigate over long distances using the five senses.
There shikigami are used by Mystical Investigators when they were restraining criminals
These shikigami are those whose vessels serve as their bodies.
These shikigami are often a Servant-type, capable of acting to their master's wishes and protecting them by remaining in another dimension until summoned. They require a constant spiritual connection with its master even when it's not summoned. Because of this, the master must have spiritual energy large enough for the shikigami to be summoned. Their 'defensive' title comes from 'Dharma-defenders' of Vajrayana and Shugendo Buddhism, and they are often customized for the user, which makes them expensive.
These shikigami are operated by their practitioner, who is otherwise unable to reach someone. They are merely a vessel in which the practitioner can communicate with someone else, a remote-controlled body.