Cha Dae-Woong, a spoiled university student and an aspiring actor, accidentally unleashes a legendary nine-tailed fox (gumiho) sealed inside a temple painting. Fleeing in fear, he suffers a life-threatening fall but is saved by the gumiho, who takes the form of a beautiful woman and places her magical fox bead inside him to heal him. In exchange, she asks for his help in learning how to live as a human. Dae-Woong reluctantly agrees, hiding her identity and introducing her as “Mi-Ho.” As they navigate their strange new arrangement, fear gives way to affection, and Dae-Woong finds himself falling for the cheerful, meat-loving Mi-Ho. But Mi-Ho’s dream of becoming human comes with a hidden cost. A mysterious half-human named Dong-Joo tells her she must have a human carry her bead for 100 days, but secretly withholds the truth––when the time is up, that human will die. As the countdown begins, Mi-Ho and Dae-Woong are forced to choose between their future and each other.