The shape of a five-pointed star drawn with five straight strokes.
Wiccans (a modern witch religion) use a pentagram with three points up as a holy symbol, often drawn within a circle, while Satanists use a pentagram with two points up, often inscribed in a double circle with the head of a goat inside the pentagram.
In Japanese culture, this symbol (五芒星) is strongly associated with Abe no Seimei, Japan's most renowned onmyouji.
