What are real ninja swords made of?

Traditional Japanese swords are made of a special type of steel called tamahagane. Tamahagane is created using a unique process by which layers of steel with different carbon concentrations are piled on top of each other. After a billet is formed, the signature curving of Japanese swords may be attained.

While ninja swords are commonly referred to as "ninjato," there is no physical or historical evidence that such swords were used. Ninjato swords are similar to katanas, but they are shorter. It is believed that ninjas, like samurai and other Japanese warriors of the feudal era, used the traditional katana instead. No known ninjato swords were made prior to 1964.