The international training organization of Masaaki Hatsumi. Founded in the late 70's, it's dojos teach Bujinkan Budo Taijutsu all over the world. The name, roughly translated, means House of the Divine Warrior.
Each dojo is lead by a shidoshi, who oversees training, and awards grades. Classes are often taught by the shidoshi, although sometimes senior students teach as well.
Most Bujinkan Dojos follow a system of 9 kyu grades, which are then followed by 15 dan grades.