Gu Wol Ryung is a male gumiho,that has a particular fondness of eating human livers. Wol Ryung however, serves as the sole caretaker of the forest in the mountains and thus does not get involved with humans often. That is of course, until his curiosity is caught by Yoon Seo Hwa, a young woman in serious trouble. Acting against the advice from Su Jong, his human monk friend, Wol Ryung decides to rescue her and brings her to his cave. They eventually fall in love and marry, living a peaceful life in the mountains. All is well, except that Seo Hwa is unaware of his true identity - and before she finds out, Wol Ryung is determined to give up being a gumiho and instead become a real human for her sake. To do that, he must follow three rules - 1) Refrain from eating any kind of meat; 2) Help all humans in need that he meets; 3) Keep his true form hidden. If he manages to keep these rules for 100 days, along with prayers and Su Jong's guidance, he will become a human. However, should he fail, he will then be doomed to become a demon/evil spirit for 1000 years. Fast forward; Wol Ryung has almost reached his goal when disaster happens - Seo Hwa is attacked by the men she ran away from, and in his attempt to rescue her, Wol Ryung reveals his identity. Frightened and disgusted by this sudden discovery, Seo Hwa betrays him, and Wol Ryung ends up being slayed. Seo Hwa later gives birth to a son, Kang Chi.

Kang Chi: