Here is a simple explanation of what the Bujinkan is all about.
The Bujinkan has evolved from old Japanese martial art (Kobudo), dating back over 900 years.
Through the years a new master is chosen by the present master to take his place with this comes they handing down of the original documentation (scrolls). As these passed down from master to master some schools have become amalgamated till only one master remains as the sole master of this lineage and the nine schools of the Bujinkan and he is Grandmaster Masaaki Hatsumi (Soke).