>>280821435
Late 90's.
They went to full-scale war probably as a result of the worsening conditions around the world as Yoru predicted.
Also Yoru's existence in itself made war a thing again, while in her weak form, war had pretty much been forgotten about.
It's also why humans are willing to go to war with Devils now too instead of just standing there and taking it from them like a bunch of cucks.