Shikigami (式神) is the term used for the summoned spirits of an "onmyouji", a Japanese sorcerer. Shikigami are used to protect and serve their master, much like the Western concept of the witch's familiar. There are many types of shikigami described in legend, the most common type being enchanted paper cutouts that can produce the illusion of another real-life object.
Shikigami often share a special link to their masters, which may cause their onmyouji to receive sympathetic injuries dealt to the shikigami. Because of this link and the enormous amount of energy needed to maintain shikigami, onmyouji do not usually summon more than one or two shikigami at a time.
Shikigami in Touhou
In the Touhou Project, shikigami are distinct entities that have been converted into a shikigami through a certain technique. For example, Ran Yakumo was originally a fox that transformed into a youkai, but now serves as Yukari Yakumo's shikigami. In this role, she is bound to do what Yukari tells her to.
Though it can be assumed that possessing a shikigami requires a large amount of energy in the Touhou universe, Ran has been around long enough and is powerful enough to have a shikigami of her own, Chen, who was "converted" from a youkai being the same way she was.
Hieda no Akyu describes this process of converting a being into a shikigami with the word "installing", as if one was installing software onto a computer. (On this point, there have been many sayings in Touhou that likened Shikigami to computers.) Even Yukari compares a shikigami to a computer. By putting on such a formula, getting angry would be understandable if program does odd jobs or does not work, though Ran in her case doesn't seem to complain when getting punished by her master and is rather satisfied.
Characters under this Bestiary
- Wikipedia entry for Shikigami