The Bujinkan Nassau Dojo only accepts students 21 years of age and older. No exceptions. This keeps the training intensity at a level appropriate for all students.
Ranking structure begins with kyu grades below the rank of black belt. Kyu ranks wear green belts. Beyond this ranking there are ten levels (dan) of black belt. To attain 5th dan, the practitioner submit to a test before the Hatsumi Sensei to establish that they are able to sense the presence of danger and evade it, considered to be a fundamental survival skill. This is called the sakki. A practitioner ranked as godan can apply to become a licenced teacher (shidoshi). A shidoshi is entitled to open his own dojo, and hand out ranks up to 4th dan as he wishes. A person who has been given 10th dan (judan) in the Bujinkan is often referred to as a shihan.