Beware The Hannya Mask
The Hannya mask 般若 is said to have come from beautiful women who are scorned by a lover--betrayed by those they love or are left behind for another woman.
Folklore: Uji no hashihime prayed to a deity to turn her into an oni so she could kill her husband, the woman he fell in love with, and all of their relatives.
To accomplish this, she bathed in the Uji River for 21 days, divided her hair into five horns, painted her body red with vermilion, and went on a legendary killing spree. Besides her intended victims, anyone who saw her instantly died of fear.