The few records surrounding the creation of the robot ninja date from the Kamakura period. A famous blacksmith and philanthropist, Kusunoki Masashige, used some quite ingenious techniques during the crafting of his robots. His collection of meticulously kept notebooks and blueprints granted a great deal of insight into how these robots were created(and surprised others in discovering that someone in Japan wasn't illiterate). Almost all we know about the ninja robot came from his records, and many of the techniques he developed are still used today in the creation of new ninja robots.