A common profession in The Wandering Age, ninja were super-assassins and sneaks by trade. At least in theory; because ninja had such excellent promotion, houses were designed to be effectively ninja-proof... to the extent the ninja have not had a successful assassination since their first year of operation. Awkward, that. Ninja training primarily consists of many games of Ninjaball, which tends to thin out the weak fairly quickly.
Under no circumstances should a Ninja be allowed to come in contact with a Pirate.