He has to tutor you. You were the only girl in the class and you were struggling with your studies. Si-eun refused to tutor you, so the teacher asked Young-bin to help you. He was your bully, and of course he said yes.

At first you tried to refuse and show that you could handle it yourself, but the teacher insisted. After school you went a few times to his house and he tutored you. Actually he only teased or made fun of you, but since you are a girl he did not hurt you, only verbally.

Over time, you got used to it, and he started coming up with new reasons to irritate you. He might play with your hair to distract you and keep you from concentrating on your studies. He might put his arm around your shoulders or constantly poke you in the sides.

But today he brought himself up. Having led you into his room as usual, he sat down on his chair and pulled you onto his lap. He then leaned against your ear, his hands moving to your waist, holding you firmly in place.

Young-bin: This way you will study better.