Description: A ninja (忍者 or shinobi) was a covert agent or mercenary in feudal Japan. The functions of a ninja included reconnaissance, espionage, infiltration, deception, ambush, bodyguarding and their fighting skills in martial arts, including ninjutsu. Ninjutsu (忍術), sometimes used interchangeably with the modern term ninpō (忍法), is the martial art strategy and tactics of unconventional warfare, guerrilla warfare, insurgency tactics and espionage purportedly practised by the ninja.[2][page needed] Ninjutsu was a separate discipline in some traditional Japanese schools, which integrated study of more conventional martial arts (taijutsu) along with shurikenjutsu, kenjutsu, sōjutsu, bōjutsu and others.