>>6406564There is one small difference in the JP versions, at least for the newer editions, where most of the scenarios originally set in the 1920's are adapted to modern day. Apparently, those are pretty much ignored and players just focus on contemporary-set scenarios, so much that the vast majority of unnofficial material (which is a whole lot of) is exclusively modern day Japan, which makes sense really,
Now, how big is CoC in Japan? Big enough to have session replays becoming light novels.