A ninja suit as described by Masaaki Hatsumi (In the book- The Way of the Ninja: Secret Techniques) is described as the "Way of the Three Cloths" which requires three cloths, all of them should be three foot in length. It should be tied in such a way near the head that the mask is totally flexible in design but should also be steadily bound.
There is no proof that ninjas initially wore only black-suits. Instead it is speculated that they dressed in the same armor as samurai or Japanese peasants. According to myth Ninjas used the same techniques which are being used by spies now days. A ninja would dress up according to his surroundings some times like a priest or at times like a samurai. They also learnt how to fight with what ever was available to them.
There is no proof that ninjas initially wore only black-suits. Instead it is speculated that they dressed in the same armor as samurai or Japanese peasants. According to myth Ninjas used the same techniques which are being used by spies now days. A ninja would dress up according to his surroundings some times like a priest or at times like a samurai. They also learnt how to fight with what ever was available to them.