story about gumiho

Legends tell that while the Kumihoo is capable of changing its appearance, there is still something persistently fox-like about it; its countenance changes, but its nature does not. In Transformation of the Kimono (구미호의 변신), a kumiho transforms into an identical likeness of a bride at a wedding. Not even the bride's mother can tell the difference. The kumiho is only discovered when her clothes are removed. Bakh Mun-su and the kumiho (박문수와 구미호) records an encounter that Pak Munsu has with a girl, living alone in the woods, that has a fox-like appearance. In The Maiden who Discovered a Kimono through a Chinese Poem (한시로 구미호를 알아낸 처녀) the kumiho was ultimately revealed when a hunting dog caught the scent of the fox and attacked.
Although it is typically depicted as a woman when it transforms into a human being, the kumiho in the tale of The Maiden who Discovered a Kimono through a Chinese Poem (한시로 구미호를 알아낸 처녀) turns into a young man that attempts to trick the maiden in marrying him. However, this is the only case in which it transforms into a man.
Although they are considered as having the ability to morph into other forms, the true identity of a Kumiho was said to be zealously guarded by the Kumihos themselves. There are also legends in which these transformations are said to be involuntary.
It is unclear at which point in time Koreans began viewing the Kumiho as a purely evil creature, since many of the ancient texts mention benevolent Gumihos assisting humans. In fact, many older texts make more frequent mentions of wicked humans tricking kind but naïve Gumihos.
As the mythology of the Gumiho evolved, it was later believed that a Gumiho had to consume human hearts in order to survive. In later literature they are often depicted as a blood-thirsty half-fox, half-human creature that wandered cemeteries at night, digging human hearts out from graves.
Like all other monsters, the Gumiho was thought to grow wise with age and with enough training, eventually learn to morph itself into various forms, including humans. Thus, they are often depicted as beautiful young maidens that trick unsuspecting men and later consume their hearts.
Another version was that the Gumiho must eat livers. This was because the liver contained the energy of a human, meaning that it processes the food and gives energy, therefore making it the container of the life force of a human. The fairy tale The Fox Sister depicts a fox spirit preying on a family for livers.
Another version of the mythology, however, holds that with enough will a Gumiho could further ascend from its Yokwe state and become fully, permanently human and lose its evil character. Explanations of how this could be achieved vary, but they sometimes include aspects such as refraining from killing or tasting meat for a thousand days, or obtaining a cintamani and making sure that the Yeoiju saw the full moon at least every month during the ordeal. Unlike Yeoiju wielding dragons, Gumiho were not thought to be capable of omnipotence or creation at will since they were lesser creatures.
The idea of a beast becoming fully human is in fact quite heavily embedded in Korean mythology, such as the case in which a bear becomes a woman through a harsh ordeal in the Dangun mythology.