This is an example of "passing the guard" using "Ninpo-style" concepts. The first concept is the same in Ninpo and BJJ and that is posture (Kamae) Knees wide, butt down and face in the chest/belly. Hands inside the arms on the biceps or inner elbow and not on the ground. Ninpo will use the same...

Ninjutsu Choke Technique

Ninjutsu

Empty hand Combat

Defense from Shizen No kamae(natural posture)