When reduced to their common denominator, kami (神) are Japanese “gods” or “spirits.” However, as with youkai, if one places Western convictions to the Japanese notion, the true essence of what kami are will be grossly misconstrued. Again, translations are halfway points for discussion’s sake—never to be taken in absolutes.
Kami come from the Japanese native Shintō (神道)—way of the gods, which at its heart, is simple (as in unadulterated) nature worship and ancestral piety. There is also a focus on purity and cleanliness. Filth and impurity correlate to evil and bad energy.
Though classified as a religion, some scholars will argue otherwise as Shintō lacks elements that define “religion.” Ethic codes, a founder, doctrines/texts, thoughts of afterlife that one may associate with Japanese religion are actually Buddhist principals. Shintōism and Buddhism are tightly interwoven, perhaps because Buddhism fills the gaps the Shintōism “lacks,” but the two are distinct and separate practices. Shintōism’s focus is life, Buddhism’s focus is death; it’s said one is born Shintō and dies Buddhist due to how the practices are applied to the stages of one’s life.
Kami are not 1) capital “G” God, the Person, and 2) not fully lower case “g” gods, as with other cultures, like ancient Greece—though this concept is closer. It is said there are eight million gods to Japan, and that’s because of how vaguely and widely “kami” may be applied. The Western sense of “god” is fixated and boxed. Kami are more fluid and free form.
Kami can be broken into two categories: amatsukami and kunitsukami. Amatsukami are the “heavenly” deities, such as Amaterasu (the celestial grandmother to the current Japanese imperial line). They are nationally recognized, and traditionally, were considered to be higher class. They are appointed to manage or control something. Kunitsukami are “earthly” deities. They are more strongly associated with nature and known only to their selective local regions. They are the thing itself.
For comparison’s sake (as the halfway point), think of the difference between the Olympian gods, the lesser gods (the Fates, the Muses), and the nymphs on earth. Amatsukami are the Olympia gods of the Japanese pantheon, kunitsukami are nymphs.
In anime/manga, when the character is the kami of (for example a tree), this is most likely a kunitsukami. In these cases, the *tree* and the kami are one in the same—they are not separate entities. Do not think that the kami lives in the *tree,* they are in fact the *tree* itself. They are *tree*-ness. Because an element of nature is so wondrous that it captivates passersby to stop and admire it, it takes on a power of its own, developing a soul. The soul is what manifests into the visual representation of the kami. Like with humans, we have our spirit and our body; we are both and neither of these components alone. Kami too, are the “persona” and the natural object.
When it comes down to it, kami are any natural object or earthly phenomena that evokes strong emotions of awe. For as grand as the thing is, how could there not be anything more?
Really well done explanation of these concepts, thank you!