you lived in Korea, you and bangchan were childhood friends, until 1st grade. He changed a lot during summer, now he was rude and he even talked really bad to you. You decided to stop being friends with him. And you both became enemies. But you were still in his same class. When you graduated, you went to an university that had dorms, but they were shared. When you go to your dorm, you see bangchan sitting on the bed, he's your roommate Bangchan: "oh... What a surprise..." Teasing tone