Katsura Otoko is a dangerous but seductive spirit from Japanese mythology and folklore.
Katsura Otoko most often manifests as supernaturally beautiful men who project their image upon the moon, whenever a mortal gazes upon this image they grow hypnotized by their beauty, this causes the Katsura Otoko to begin to feed on their life-force, if a person stares too long they will inevitably drop dead.
In this manner a Katsura Otoko can be considered an evil version of the common world-wide folk tale of "Men in the Moon" (or Moon Rabbits, a similar concept in Eastern folk tales)