Tamamo-no-Mae is a kyuubi-no-kitsune ('nine tailed fox' - a fox that gains spiritual and ghostly powers is a kitsune, and they gain one extra tail for every century they train in their powers). She is often grouped in the Four Vilest Youkai ('youkai' usually means 'monster') of Japan - the other three being Shuten Doji, Nurarihyon, and Sutoku Tenno.
Tamamo first appeared as a young and beautiful woman in the imperial courts of ancient Japan. Her beauty, grace, wisdom, exotic aura, and even her alluring scent instantly turned her into a figure of fame and power amongst the imperial members and government officials. However, she was eventually exposed, and she fled. She was eventually killed in a brutal war, and her body turned into the Killing Stone - which was cursed by Tamamo herself so that all life within a certain radius from it would be cursed to death.