By chance, the ignorant rich boy Cha Dae-woong (Lee Seung-gi) rescued the nine-tailed fox (Shin Min-ah) who had been sealed in a painting in the Samsin Temple for more than 500 years. The fate of this man and this monster has been linked together ever since. The nine-tailed fox came to Seoul with Dae-woong. Modern civilization made this mythical monster make a lot of jokes. She is very smart and loves to eat meat, which adds a lot of fun to the life of the carefree and witty Dae-woong. As time goes by, they play and fight, and gradually develop feelings. Dae-woong has the fox bead of the nine-tailed fox. After absorbing 100 days of popularity, this bead will turn the nine-tailed fox into a human, but this will sacrifice Dae-woong's life. In this materialistic and cold modern society, how will their mythical fate end?