A couple of weeks ago I wrote a post about a booklet of instructions for matsuri that Jinja Honchō had prepared for sōdai across the country. One of my readers asked a very reasonable question: given that matsuri vary a lot from place to place across Japan, is it actually possible to provide instructions that apply to everyone?
The short answer to this question is “yes”, but things are a bit more complex than that suggests.
While it is true that there are a lot of variations across Japan, there are also, these days, a lot of close similarities. When Shinto was under state control in the first part of the last century, all jinja were legally required to perform their matsuri in the same way, with the same actions, the same vestments, and the same offerings. Even then, there were exceptions for important local traditions, but those had to be performed in addition to the standard matsuri, not instead of them.
With the end of the war and the disestablishment of Shinto, the legal requirements disappeared, but Jinja Honchō continued to train priests in a particular form of matsuri, and issue regulations saying that matsuri should be performed that way. The overwhelming majority of jinja perform the overwhelming majority of their matsuri according to these guidelines. This has a number of advantages; most significantly, priests trained centrally can go to work in any jinja, and know how to perform the matsuri there.
Of course, there are unique matsuri as well, and priests have to learn to perform them if they start to work at those jinja. In many cases, the new priests have been helping out at those matsuri for as long as they can remember, because many priests are hereditary, but when they are not, they can learn from the people who are performing the matsuri, and have kept it alive.
And this brings us to the reason why the instructional booklet is possible. It is true that some jinja have unique rituals associated with their matsuri, but if they do, the sōdai know what they are, and do not need the booklet to tell them what to do. The booklet is necessary when a jinja does not have a strong, living, local tradition to rely on, and so the sōdai are not entirely sure what they should be doing. In that case, in contemporary Shinto, one would naturally fall back on the default matsuri defined by Jinja Honchō, and that is what the booklet explains.
For many purposes, the ritual guidance provided by Jinja Honchō these days is a default form, to be followed if a particular jinja has no unique local custom to follow instead. Because most jinja have no particular local tradition for most matsuri, the standard form is extremely common, but Jinja Honchō does not try to suppress local traditions that treat things differently, at least in general.