Just a note to those who don't know what a gumiho is (I didn't know till I watched My GF is a Gumiho), a gumiho is a legendary nine-tailed fox. When they are in human form, they are stunning woman and legend has it the gumiho takes the liver of men and eats it. In this drama, the woman had no means of killing people but just wanted to keep herself hidden from humans and try to live as a human and try to protect her daughter from harm.
The gumiho, a stunning woman, is telling her daughter, Yeon Yi, of the love story of the gumiho. No one knows that this woman is a gumiho. The love story started out with her husband encountering the gumiho in "monster" form. The gumiho said that she will spare the man's life but he has to promise to not ever mention the gumiho again. He promised, doing whatever he could to spare his life. Then as he left the forest, he encounters a beautiful woman (the gumiho in her human form) and they get married. Apparently, if the gumiho gets married for ten years with a mortal, she can become human. However, the day before 10 years was up, the man mentioned the gumiho and the gumiho lost her chance of becoming a human.
However, if there is a girl who is born on the same month, day, year, and time as the sick girl, Cho Ok, the sick girl would get better. When Yeon Yi and her mother appeared, Cho Ok got better. In order for the girl to be better forever, it meant that Yeon Yi had to be sacrificed and Cho Ok will have to eat Yeon Yi's liver. However, in the time being, they lived there. A young master and Yeon Yi start forming a love relation and the mother also had a kind man liking her and the master of the house also started liking the gumiho too.
The mother and daughter suffered quite a lot in this household. Cho Ok constantly bothered Yeon Yi, even making the servants throw Yeon Yi into a well. The mother of the household also bothered Yeon Yi's mother. Thankfully, a servant who also liked the gumiho and didn't care if she was a beast or not or the fact that her child was also a beast, always helped the mother and daughter as best as he could. Cho Ok was also extremely bratty. Throughout the time, Yeon Yi began to notice changes as she sometimes would transfer into a fox figure. The master of the household, the father of Cho Ok, did not want to kill Yeon Yi as he started feeling something for the mom. However, for the sake of his own daughter, the master killed Yeon Yi and gave Yeon Yi's liver to his daughter.
I liked the ending because it was sweet, but I felt really bad for the two guys that liked the mother-daughter pair. Anyways, enjoy this drama! You truly should watch it! It's a fast watch and you get hooked on this pretty fast too.