Shin Woo Yeon is a handsome and intelligent professor. He is also a 999-year-old nine-tailed fox. To become human, he gathers human energy in a pearl, and is almost on the verge of becoming human. Lee Dam is a university student. One day, an incident occurs that changes the fate of these two people. Shin Woo Yeon’s pearl falls into Lee Dam’s mouth, and she swallows it unintentionally. The pearl can only remain inside the human body for one year; after that, it will shatter and Lee Dam will die, whilst Shin Woo Yeon will lose the chance to become human. So the two find themselves living together until they can find a solution.