Scar was a Daimon supervised by Kaolinite, created from the fusion of a Daimon Egg with a scarf belonging to Haruka Tenou. She attacked Makoto Kino for her Pure Heart Crystal.
Though Scar originally appeared with a cloak and a monstrous-looking face, she was later revealed to be wearing a mask, and abandoned the cloak when she attacked. http://www.wikimoon.org/index.php?title=Scar