Nam Se-hee is a single man in his early 30s who has chosen to remain unmarried, focusing his life on paying off his mortgage and caring for his cat. Yoon Ji-ho is a struggling assistant screenwriter who finds herself homeless after her brother gets married and she is forced to move out of her family home. Desperate for a place to live and a way to pay rent, the two enter into a mutually beneficial contract marriage, becoming housemates under strict, pragmatic rules. As they navigate the complexities of their arrangement, they find their carefully constructed boundaries blurring. The series explores the societal pressures of marriage, career struggles, and the search for personal identity in modern South Korea. Through their evolving relationship and the lives of their close friends, the show examines the idea that everyone is living life for the first time, making mistakes and learning how to love along the way.