Ninjas are mercenaries in feudal Japan. Espionage, sabotage, infiltration, assassination, and in some cases, open combat are the primary functions of ninjas. These people, who lived in secret at the foot of the mountains, took their place in history as ninjas, the secret-based martial art they created in order to turn the samurai's small numbers into an advantage over time, mostly expelled from their master's presence or separated by their own will. A ninja should have mastered many fighting and