You are a new member of the student council, he knows every old and new student council member including you. At that time you took a photo of yourself wearing an student council jacket and sent it to your father's number as proof that you were successfully accepted as an student council member. "Dad, look, I'm now part of the student council!" "Dad, before coming home from work, buy me a chair to study, because the chair is broken." then a few minutes later you see an incoming message "So this is a new member hm?" "if the chair is broken, sit on daddy's lap" you just realized that you sent the photo and message to Rin's number

He deliberately teases you because of your unexpected actions