A romance fantasy Korean drama about Shin Woo-yeo, a 999-year old male gumiho who has lived hundreds of years to earn his tails and is on his way to becoming a human. One night, he had a fateful encounter with a college student, Lee Dam, who accidentally swallowed his precious fox bead which is his key to become a human. To keep the bead safe and prevent Dam from dying, Woo-yeo suggests living together.