Ōmagatoki

Ōmagatoki (逢魔時 or 大禍時) is a Japanese term referring to the moment at dusk when the sky grows dark. Opposite of Akatsuki (暁). It has specific meanings for the two ways of writing it: first, "the time of meeting yōkai, yūrei, and dark creatures"; and second, "the time of great calamity".

In Illustrated One Hundred Demons from the Present and the Past, Toriyama Sekien described ōmagatoki as the time when chimimōryō, the evil spirits of the mountains and rivers, attempt to materialize in the world.