ㄜ is a chinese character often depicted on the forehead (and, less prominently, other body parts and/or equipment) of Demons in artwork dating to Earth IX and early versions of Midgard. As far as I remember, the use of the symbol was in turn inspired by its use in artwork by someone who participated in the Anime RPG. The symbol is a chinese character, but I wasn't aware of that when I began using it - I interpreted it only as a bent, crooked christian cross. I think to remember that the use of the symbol by the person in the Anime RPG group was in turn inspired by the symbol's use in a manga that person had read.