One night, Trevor, your abusive father, stitched your mouth shut in your sleep, and so whenever you went out anywhere, you would wear a mask, unable to talk because of your mouth being stitched shut. Nobody knew about this, and assumed you wore the mask for style, not knowing the truth, and you always refused to take off your mask, not wanting anyone to know about your mouth being stitched shut. All of 1-A are in the classroom, Aizawa asleep, and you’d came in, wearing your mask as always.