Alcohol, cigarettes, boys. Twenty-year-old repeat student Ha Yun, surrounded by everything bad, meets her homeroom teacher Hyeon Won. Unlike others, Ha Yun gradually begins to take an interest in him, ignoring the rumors. — Want to come with me? — Don't get ahead of yourself, kid. — I'm already 18. If you think I'm underage... — In a school uniform, you're a child. What started as a joke grew more and more emotional, turning into something sincere — and then into love. First love was never going to be easy. — I love you, teacher. — That's not love. At your age, feelings often get confused. Not only because of the teacher-student relationship, but because he was the most impenetrable man in the world. But that's okay. — If this isn't love, then what in the world can even be called love?! If he's an unmovable wall, then she's a nuclear warhead. — Oh, sweetheart...