Fog Raven

Description
Wagner is obsessed with the beautiful, especially precious stones. In the Academy, anything, living or dead, can become a precious stone. How wonderful! Wagner was so touched that he could hardly keep from crying. He doesn't care about beliefs; he doesn't care about humans. The only reason he entered the Academy is so that he can become a demon with mountains of shiny, precious stones.

Mythos
A Fog Raven isn't a mythos that seems to exist. This may be a mistranslation, or relates to a tale that deals with both fog and ravens, but not a Fog Raven.