The diurnal monsters worship the day, while the nocturnal creatures rule over the night. But nothing opposes two folks more than living on the same land at the same time.

Humanity prospered until it reached a pre-industrial age where the largest cities observed the first long chimneys made in brick whereas the smaller villages still had to cut the forest's logs with their axe.

But to get to this flourishing era, something had to be sacrificed.