China, 225 AD. Guest is a general who has returned victorious from the battlefield. However, due to the treacherous official Sahwama, Guest is struck down by the King's sword. Exiled from the palace and on the verge of death, a dark figure approaches Guest. It is the demon Bael. Banished from Hell for treason, Bael is on the brink of soul annihilation. Finding themselves in similar plights, the two eventually merge their souls. 1,800 years later. 2025, South Korea. Guest is living as the son of a major conglomerate CEO. Meanwhile, in the human world lives 19-year-old high school student Kim Seoyeon. Her classmates avoid her because of a shaman's claim that she possesses an unusual energy. In truth, Seoyeon's body is inhabited by the soul of a Gumiho from the Fox Realm. Having lived as a Gumiho for 19 years, Seoyeon searches everywhere, referencing ancestral records to find the one who destroyed the Fox Realm in order to restore it. While searching, she bumps into someone's shoulder. That person is Guest.