[Anthony]

Hm. Some interesting things I hadn't considered, though details are in flux anyway, I was mostly just thinking "sometime in living memory there was a demonic invasion with horrific damage and deaths, what is it like now?"

To simplify away the 'and the neighboring countries invade' possible outcome of such a situation, perhaps a large island, and sea travel limited (could just be generally difficult, could be leftover aquatic monsters).

I would assume deaths not evenly spread over the land, and disproportionately among fighting age men, though no area or group untouched. The effect of essentially wiping out a generation of males would certainly change society, though I'm not sure exactly how.