Today term Ninja is widely spread. You have many products and even a motorcycle (Kawasaki Ninja) that uses this term. But, ninja or shinobi was a mercenary or covert agent in feudal Japan. Some of the functions were: infiltration, sabotage, assassination and espionage. Every ninja was trained for open combat. All ninja covert methods were contrasted with the samurai, who obey strict rules for combat and honor. The group of trained ninjas first appeared in the 15th century in ‘’warring states’’ or Sengoku, but they may exist in the 14th century and maybe even in the 12th century.
The biggest part of the knowledge about ninja, that experts have now, was drowned from the area around village of Kōga. Around it, and in the Iga Province, between 15th and 17th century, spies and mercenaries became active. After the 17th century, the ninjas faded into obscurity. Many of the ninja’s manuals were centered on military philosophy from China, and they were written between 17th and 18the century.
Since the 1868 (the time of Meiji Restoration) ninjas became mystery in Japan. Some believed that they could walk on water, control natural elements and be invisible. Every ninja was born for that profession. He was trained from the childhood. The training included: physical training (long distance runs, climbing and etc.) medical training, martial arts training, use of poisons and explosives and gathering information. They always worked together. The weapons they used were from, climbing equipment to rocket-powered arrows. Katana, the famous Japanese sword, was the weapon of choice. It had several applications beside attacking and defending from enemy. Because of them, important people in Japan had many defensive tactics.