A fundamental aspect of Ninjutsu was represented by the methods of infiltration into enemy's territory, to cause disorder, to gather information, to spread false information, or simply to kill the enemy's leaders in order to help with a victory. As explained in Bansenshukai, a 17th century document written by Fujibayashi Sabuji, with chapters about special weapons, philosophy, astronomy, history, topography and more, such spying and stealth  techniques were part the basic training that made ninja warriors so famous.

The Bujinkan is an international organization founded by Grandmaster ( or more accurately, "Soke" in Japanese. Pronounced Soe-Kay) Masaaki Hatsumi, the Thirty Fourth. generation inheritor of the Togakure (Toe-gah-koo-ray) ryu of ninjutsu as well as 8 other ryu (style, school, tradition) called "The 9Traditions". Of these 9, 3 are ninjutsu, 3 are samurai and 3 were used by both samurai and ninja.  They have been passed down from generation to generation, some for close on One Thousand years. The Bujinkan was devised by Hatsumi-Soke as a way to transmit the life enhancing knowledge he learned from Toshitsugu Takamatsu-Soke, the 33rd. generation inheritor.