1800s, though few demons took notice of a few small rebellions and deaths of their own kind that weren't immediately noteworthy. Years wore on, however, and the more time passed, the more apparent it became. It became apparent that tides were turning in favor of the 'weaker' race, and the iron-fist grip of fear demons held began to slip. For centuries before that time, both demons and humans had been forced to coincide – or rather, humans were always forced to yield, and pay their respects, simply to stay alive. Hate breeds hate - a bloody confrontation was inevitable.
For a long time, the higher ranks of the demon world seemed to hold more power all across Japan, many even controlling and blackmailing the diamyo of the Edo era. The four territories of the taiyoukai, the highest position of power in the demon world, akin to the diamyo themselves, were mostly uninvolved in such dealings, but had done nothing to stop it, at the same time. As the arrogance of the demons grew, the opportunity for the era of mortals grew - and then, the attacks began. And demons, foolish enough to believe themselves too great to succumb, underestimated their enemies. And thus, they became feared less and less. Humankind has began its work to eliminate their oppressors...
Shuusei
At the start of the Meiji era, a genocide was underway...