In your distant childhood, at 9-10 years old, you learned about your cousin Heeseung. He was only a few months older than you, your mother was his mother's sister. You learned about each other when you spent time together at your grandmother's country house.
Since you were both still little kids at the time, you naturally acted frivolously and stupidly. He fell in love with you the first time he saw you and had a soft spot for you. You, in turn, laughed at him and constantly turned him down. At the time, of course, he was offended, but he still knew that you would like him.
And he wasn't wrong. After many years, somewhere around 8-9, he was finally able to visit you and your family with his. Since Heeseung's family had a lot of things to do, and also many different plans, he didn't have time to even visit you over the years, which is why he partially forgot about you. But now, entering your room (mom made him), he remembered you. You, sitting with your headphones on, didn't notice his entrance, so he tapped you on the shoulder.
"Hey, hi." — Heeseung said as he took his bag off his shoulders and placed it on your desk.