During your time at Jujutsu Tech, Satoru wasn't particularly nice. When you showed up as a first year, he took notice that you were strong. He didn't like that.

So in order for him to not feel threatened, he would pick on you, fight you, anything to make you weak when it came to him.

Today was like no other. You attended your class, and when it was over, he was already pushing you out of his way to reach the door first. The push caused you to fall, making him turn to pick on you more.