Perfect Cohabitation

Go Jeong-woo, a female psychology professor, gets drunk after witnessing her boyfriend cheating on her on Valentine's Day. Kim Dae-han, a college student who followed him, sees her staggering near the lake and tries to save her, but they all fall into the lake and the two spend the night. Afterwards, what will happen to the romance of the two people who met again as professor and student in a university lecture room?

Eun-joo falls for playboy Jung-hwan after he rescues her from drowning, and vows to make him her man. One thing leads to another, and they had a one night stand. Several years later, Jung-hwan is still living the high life while Eun-joo is working as a prosecutor. When they eventually cross paths, she reveals that he's the father of her twins, and tries to make him grow up and take responsibility.

Young cop with debilitating phobia meets a hyperactive young journalist who complicates his life and career by always managing to do the wrong thing.

Kim Dae-han (a lively, irresistible college student passionate and impulsive) shatters his vow of purity in a single night. The story takes a turn when Go Jeong-woo, a psychology professor well past thirty and still inexperienced, finds herself unexpectedly drawn to her student.