One of the regular columnists in Jinja Shinpō is a Shinto priest and folklorist based in both Okayama Prefecture in western Japan, where he is the hereditary priest of a jinja, and in Tokyo. He apparently uses the Shinkansen a lot.
In his most recent column, he talked about some traditional rituals that are performed in the area around his jinja. There are, apparently, three levels of kami. The Ujigami covered a fairly large area (several villages), and people participated in the matsuri based on social ties. The Ubusunagami covered a single village (roughly — the terms have no exact English equivalent), and people participated based on geographical ties. Everyone who lived in the village was part of the matsuri. Finally, the Kabugami (or maybe Kabukami; there are no kana to give the reading in the article) were honoured by single families, both by the main household and by branch households.
Rural depopulation and the ageing population is apparently having a negative effect on all these matsuri, but most so on the Kabumatsuri, because the group supporting this matsuri was smallest to begin with. Traditionally, the matsuri was performed in late December, and had two components. One was performed at the home of one of the families in the group, which would then host the kami for the next year, while the other was performed at the jinja for the kami.
The column was about one of these matsuri. The family involved had dropped to four households, of which two had moved out of the area, leaving just two households to support the matsuri. That is really not enough, and it had been seven years since the matsuri was performed.
However, this year the two families contacted the priest, and asked him to perform the jinja part of the matsuri in early May, at the end of the extended holidays for the Imperial succession. The families that were still in the area contacted the two that were not, and the heads of both of those families came to attend. When the priest arrived, the four men were all in overalls and dripping with sweat, because they had been clearing undergrowth around the jinja and cleaning it. They then dusted off their overalls and performed the matsuri with the priest; with the five of them kneeling in the prayer hall, the space was almost full.
The priests commented that, although this involved some changes to the tradition (the time of year, the clothes, the residence of the people involved), the fact that the matsuri had been revived, and that the people involved planned to keep it going, was a very good start to the Reiwa era.
I have the impression that this sort of local matsuri is very important in Shinto, but it is hard to find out about. Jinja Shinpō is one way to find ways in to learn about them, so I hope to learn more over time.