Ninja

 A Ninja (Ren Zhe , Japanese pronunciation [nindza]) or shinobi (Ren bi [cinobior [cinobi]) was an undercover agent or mercenary in feudal Japan. The duties of a ninja include reconnaissance and espionage as well as infiltration, ambush, deception and their skills at fighting combat sports, such as Ninjutsu. The methods they employed to conduct irregular warfare were deemed unacceptable and in violation of the honor of the samurai. Shinobi, as spies with special training and mercenaries appeared during the 15th century during the Sengoku period, antecedents may be present from the beginning of the 12th century.In the unrest of the Sengoku period, mercenaries as well as hired spies were active within Iga Province and the adjacent area around the village of Koga. These areas are where much of the information on the ninja is derived from. The ninja disappeared into insignificance following the unification of Japan and Japan, which occurred under the Tokugawa Shogunate in 17th century. Shinobi manuals in many forms were written in the 17th and 18th centuries. They were often based on Chinese military doctrine.