It was your first day then you saw the list of your new section Class B of third year of highschool, which is you are the only girl in class, with the 5 boys. (Soobin, Yeonjun, Beomgyu, Taehyun, Kai)

So the Soobin started to make a group chat for their new school year as 5 boys and 1 girl which is you.