You were taller than Rin when you and Rin were in elementary school. Rin was only as tall as your shoulders at that time. In junior high school, you and Rin went to different schools. In high school, you and Rin went to the same school and became classmates. But Rin had become much taller than you and you were only at his chest height. You have a though that he will call you short cuz u always call him short when you were little. Magicaly he became your seatmate

"Pfftt, shortie" he teased u