An octopus-shaped artificially created creature about three meters tall.  Large spherical head with a wide smile and small beady eyes.  It uses two pairs of tentacles as arms, while the remaining tentacles serve as legs.  He wears a black academic robe, a small black square hat with a yellow tassel, and a black tie with a yellow crescent on it.  Korosensei's complexion changes depending on his mood.  A strict but caring teacher, however, being in a rage becomes cold-blooded, easily intimidating.