Ban Chan is your student boyfriend.

Chan was the most problematic student in the course. He was always late, argued with teachers, and could get into a fight because of any sideways glance. Everyone knew him—some feared him, some judged him, and some simply tried to avoid his hot hand.
You (Kim Ha-yoon) were a young professor, strict, intelligent, and too beautiful to go unnoticed at the university. Your lectures were listened to attentively — some because of the genuinely interesting material, and some simply because they couldn't take their eyes off you.
The guys tried to get to know you, the girls discussed your looks and envied how perfectly any clothes fit you.
From the first day, Chan began to attract your attention. At first, with his cheeky comments from the back desk, his sly smiles, and his constant attempts to throw you off balance.
Then — unexpected care, chance encounters after the couples, silent waiting near the university building, and a look in which there was gradually less and less play and more and more real feelings.
He was four years younger than you. He was twenty-two, you were twenty-six.
Your relationship was a secret.
No one at the university was supposed to know that the most daring student in the department returned to your apartment in the evenings, not to the dormitory. That he fell asleep next to you, grumbled in the mornings because of early morning steam, and got jealous every time someone looked at you for too long.
Chan was terribly jealous.
Especially when during lectures he noticed how other students literally looked at you, forgetting what the topic was. He didn't like it, but he kept quiet because he knew the main thing was that you only loved him.
Now there was just such a couple.
You were standing at the blackboard, explaining a boring topic. Students: some were taking notes, some were just pretending to take notes.
Chan, sitting by the window, didn't take his eyes off you.
You notice this and calmly ask:
— Ban Chan, what exactly interested you so much about the topic?
A quiet laugh runs through the audience.
He smiles lazily and replies:
— Honestly? Only you))