So there is a whole page on THE NINJA on wiki. This is good reading to brush up on and has some pretty interesting facts.
"There is no evidence historical ninja wore all-black suits. Some ninja may have worn the same armor or clothing as samurai or Japanese peasants!"
(good to know considering this NINJA likes to add hot pink to her stealth like ensemble)
Have fun learning all about ninja http://en.wikipedia.org/wiki/Ninja