Yobi is a five-tailed fox, who after a hundred years of living in the forest with some aliens that crashed in their spaceship, developes an interest in humans, and especially in a boy called Hwang. She is able to transform into a human (among other things), and spend time with Hwang, but since common folklore says that the nine-tailed foxes (in her case, 5) steal the souls of young men, her true identity can't be revealed.