Seonu is an average college student until his life is turned upside down by a stranger named Shin, who claims to be his lover from a past life. To make things even wilder, Shin says he's a spirit! After Seonu reluctantly lets Shin into his home, all sorts of characters come out of the woodwork: a classmate claiming to be Shin's true lover from the past, a man in black with mystical powers, and the charming owner of a café. With the help of an 800-year-old nymph, can Seonu piece together the mystery of this time-transcending love triangle?