When you go to a school full of disabled people you don't freak out when you see an amputee or burn victim. No, the ones who really creep you out are the ones who look relatively normal like Hisao. Just think about it. A bunny casually hanging out in a pride of crippled lions, wouldn't that be a seriously messed up bunny!? I'm willing to bet he has the most badass handicap here.