I just added a tag folklore (to be understood in the wider sense of "民俗学").
It came to me while posting this, but I think there are already questions that touch on similar topics, like: How are 化け物, 妖怪, 幽霊, etc. related to each other? and more, I would expect, in the future (between traditional folklore and folklore perpetuated through manga, we should have our share of demon/ghosts questions).
Generally, I think we could do with a few more "theme" tags. We have a very complete set of "linguistics" tags to describe all grammatical and technical language aspects of a question, but much fewer tags to represent broad theme categories (such as fauna or food). Ideally, most questions should fit in one such category (in addition to their grammatical tagging)...
Any objection to either of the above?
Suggestions for good, broad, category tags that could be preemptively added?
A few clarifications on SE tagging policies and the above proposal:
Tagging questions with themes that are not in themselves exclusive to the Japanese language (e.g. "culture" or "food" or "folklore"...) does not affect the established rules on what is on-topic: questions must be primarily on the Japanese language and its usage (not on unrelated aspects of culture). But obviously, most questions dealing with vocabulary or nuances will also belong under a "cultural" theme. I feel tagging this aspect would be beneficial to everybody (you may, for example, be a student of Japanese interested in aspects of the language having to do with food, or mythology etc).
It is an established convention about tags on SE, that they are implicitly always specific to the context of the site. For example grammar means "Japanese grammar" on JLU, whereas it would be "German grammar" on GLU. As such, always keep in mind when considering a new tag suggestion that its "Japanese language and usage" context is always implied: folklore is to be seen as "Japanese language and/for/in folklore".