Mingyeol is a happy-go-lucky twenty-six-year-old girl who recently quit her job. With extra time on her hands, she spends her days crushing on Tae-eun, a cute boy who works at her favorite coffee shop owned by Tae-eun's older sister Huiyeon. Mingyeol stops by every day despite Tae-eun's lukewarm reactions. What seems like a lucky break finally arrives when he asks for a favor. He hands her a letter, asking her to give it to Huiyeon a week later. Though puzzled, Mingyeol is willing to cooperate, but her own sister tactlessly opens the letter and announces the alarming news: it's a will! When Mingyeol confronts Tae-eun, he acts like he doesn't remember anything at all. Mingyeol is now armed with a mission to save her crush, but will he open up to her and tell her what's wrong?