神（かみ）
Kami
The gods and spirits of Shinto, from a great shrine to the spirit of a rock or a river.
Kami is the word for a god, and it reaches from Amaterasu at Ise down to the spirit of a single old tree. Mountains have a yama no kami; rivers and wells a suijin; a house has gods of the hearth and the privy. A kami is honoured with offerings and a small shrine, and does harm when neglected or offended.
The border with yokai is thin. A common view among folklorists is that many yokai are kami that lost their worship: the kappa as a fallen water god, offered cucumbers at the river; the zashiki-warashi that brings a house luck while it stays; the tree spirit that punishes a woodcutter who did not ask. The masked Namahage who visit houses in Akita are kami, received with sake, and the children who fear them are not wrong to.
Related yokai
Kappa
河童（かっぱ）
A child-sized water yokai whose strength lives in the water held by the dish on its head.
Namahage
なまはげ
On New Year's Eve in Oga, Akita, young men in fierce masks and straw capes go from house to house as Namahage — visiting deities who rebuke idleness and bring blessings for the year. Each household receives them with food and sake.
Kodama
木霊（こだま）
Kodama can mean both a presence within an old tree and the echo that returns from a mountain — but Japanese tradition gives it no single fixed body.
Zashiki-warashi
座敷童子（ざしきわらし）
In Tōno Monogatari, an unfamiliar child crosses the corridor of an old house — and the family that shelters the spirit is said to prosper.
Yamauba
山姥（やまうば）
A man carries a woven object home from the hills, and that night a woman's voice demands the return of her ashinaka.