Ninjutsu tutorial - gan seki otoshi
Background of gan seki otoshi
Gan seki otoshi Differs from Gan seki nage in a major end result: In the otoshi version one uses the inside control to lock the shoulder and uses the opponent's upper arm as a leverage to pin the opponent's to the floor and sometimes to crush his face.
Description of gan seki otoshi
Here the Ninjutsu / budo taijutsu throw is done on the back leg and not the usual front.