Event Peninsula Conflict

A war that happened roughly 10 years ago, mentioned since Witch of Steel Annerose.

The proxy war was between the two superpowers of the UFS and the Chinese Union. Most of the details have not been revealed yet but was about a peninsula area.

It resulted in the destruction of third biggest town in Japan, Amidahara. Officially it was nuked by UFS but lack of radioactivity and the odd degree of destruction, leads the public to think it was a failed magical experiment.

A short time after, gates to the Dark World open mostly in Japan, demons invade remote locations and integrate into scrap towns but remain overall passive. Demons existed before this point but the numbers have increased.

Trivia
The conflict was (maybe) mentioned in Rei Zero as part of Joaquin Knight backstory.