“I shouldn’t be doing this to you…” Ryu Jin-han, a close friend of her older brother, whom she happened to reunite with by chance. Just as the joy of seeing him again begins to fade, Ji Ha-yeon witnesses her boyfriend cheating on her, and Jin-han is there to see it too. After that, whenever she encounters Jin-han, something embarrassing seems to happen to her. But at some point, he starts to see her not just as a friend’s younger sister, but as a woman who catches his attention.