This romance drama tells a story about a talented superstar Jung Woo Jin (Lee Sung Yeol) who has a painful disease. He always remembers everything even the tiniest thing. This disease always brings him into a stressed situation. One day, he meets a girl named Do Hye Soo (Bae Yoo Bin) who also has a rare disease. Her memory always resets every month that making Hye Soo forgets her past memory. Their accidental encounter, bring them into hell situations that they never forget forever.