When Sowon Han woke up, a mysterious demon planted a sudden kiss on her lips and swiftly disappeared. Bewildered by the unexpected encounter, she doubts its reality until she meets her new classmate Hyeon Yu, who claims to be her past lover and protector from a bygone era. Despite Hyeon's determination to reignite their passion that spanned ancient times, Sowon cannot recall their scandalous affair. As Hyeon tries to rekindle their love, Sowon grapples with uncertainties about recovering her lost memories and Hyeon's potential demonic nature.
