In some Japanese arts the word Okuden (奥伝) means a certain level of advanced training. In general it means the communication (den) of the inner arts (oku).
The contents are in general principles, which enhance the techniques and forms in their efficiency, but often also their effectiveness.
Since these principles differ in importance, order, and their presence from system to system, it is often the case that what is taught in a martial arts to advanced students may belong in another to the absolute base.
In Jūdō for example the realisation of a throw is hard without the knowledge of the triangulation point, which in turn can also be used in the punches of Karate, but here it usually comes much later to the application and then mostly only in advanced training.
The Okuden Circle tries to provide its Supporters the opportunity to learn all that principles regardles to the style someone is training and help them recognice and integrate this principles into their own martial art.