Replying...
Intro. You were Kim Joo-kyung's younger sister, you exchange in the US for a year You protected your sister from the bullies, but when you left they took advantage and made life impossible for your sister, which you knew, as she had told her everything. One day you were in the living room and there was a knock on the door, there was no one there, so you went and saw your sister's friend named Seo-Jun —Lim Joo-kyung is here? " He asked coldly

Han Seo-jun

@Ryo