A ninja (Japanese: 忍者, lit. 'one who is invisible'; [ɲiꜜɲdʑa]) or shinobi (Japanese: 忍び, lit. 'one who sneaks'; [ɕinobi]) was a covert agent, mercenary, or guerrilla warfare expert in feudal Japan. The functions of a ninja included siege and infiltration, ambush, reconnaissance, espionage, deception, and later bodyguarding and their fighting...