Daimajin is a sort of oddball in the overall history of kaiju films, but definitely qualifies as a kaiju by virtue of the sheer over the top nature of his rampages.
(Warning: The following clip involves a fair bit of violence; while none of it is especially graphic, my sister gasped in startlement when she saw what happened to the guy who tried to escape at the end. I wasn't much bothered myself, but that's probably because when I'm in a certain kind of mood, fictional violence against horrible people tends to make me chuckle rather than cringe, and I was definitely in that zone the first time I watched it, probably because this kind of movie is exactly the sort of thing that puts me in that mood*.)
This does not look like a movie that was made the same year as Gamera vs. Barugon by the same company. (Admittedly, Gamera vs. Barugon is one of the better Showa Gamera movies, but there's still not much of a comparison.)
But considering the time period the movie was made in, setting a kaiju movie in a medieval time period seems like such an obvious choice for making the setbuilding and effect work easier (and more impressive), it's amazing that it wasn't done more often.
Although seeing every single group of medieval folks faced with a monster try the grappling hook/chain tactic might eventually have gotten old. Might have; both Daimajin-related sequences where it was tried that I've seen were pretty entertaining, by virtue of how effortlessly Daimajin turns it around on them.
(Which is frankly why I'm interested in owning these movies; Daimajin seems from context to have nearly unlimited supernatural powers, but he mostly seems content to use his indestructibility, physical strength, and the simple fact that nobody seems to realize he's an intelligent being to wade through things and just kinda be a giant, well... asshole.)
*I promise I don't have that kind of reaction if I think real people are being hurt. Actually, I find America's Funniest Home Videos hard to watch anymore, despite the fact that I can't imagine videos would make it on the show if the events in them had actually seriously hurt anyone.