Shinbutsu kakuri

When Buddhism was introduced through China in the late Asuka period (6th century), rather than discard the old belief system the Japanese tried to reconcile it with the new, assuming both were true.

As a consequence, Buddhist temples were attached to local Shinto shrines and vice versa; both were devoted to both kami and Buddha.

The depth of the resulting influence of Buddhism on the local religion can be seen for example in the fact that the type of shrine we see today, with a large worship hall and images, is itself of Buddhist origin.

[2] The influential honji suijaku (本地垂迹) theory, common in Japan until the Meiji period, even states that Buddhist gods choose to appear to the Japanese as native kami in order to save them.

[3] While in popular practice kami and buddhas were both mixed and combined in a "common religion", they were at the same time isolated and separated in various ways elsewhere.

[1] An 804 book, the Kōtaijingū Gishikichō (皇太神宮儀式帳), stipulates that on Ise lands some Buddhist words (buddha, sūtra, gojūnotō, monk, temple or vegetarian food) cannot be uttered and must be replaced with others.

[1] The book even specifies these replacement words (imikotoba (忌み言葉)) to be used instead of proscribed ones: nakago ("middle child") for a buddha, kawarabuki ("tile-roofed building") for "temple," and somegami ("stained paper") for sūtra.

[1] It is important to note that Buddhism was proscribed only insofar as the emperor was concerned and during the periods prescribed by the rites, but otherwise the usual mixing of kami and buddhas would take place.