Green Ninja Crocodile Cartoon T-Shirt for Toddler

Ninja was a covert agent or mercenary in feudal Japan. The functions of a ninja included espionage, deception, and surprise attack. Their covert methods of waging irregular warfare were deemed dishonorable and beneath the honor of the samurai. Though shinobi proper, as specially trained spies and mercenaries, appeared in the 15th century during the Sengoku period (15th–17th centuries), antecedents may have existed as early as the 12th century.