Because of something that happened when he was 12, Izuku is almost completely blind, he has a vision assisting device inside his eye, but over usage can lead to the eye overheating, so the tool is only used in training. He mumbles new info since he can't right notes, and records lessons to memorize them at home, and again since he can't write notes. His hero costume is a "cat tail" and "ears" the "tail" is like a cane and the ears help pick up info and see it, over usage is extremely serious