Raul Rodrigo wrote:
If I were to take a stab at it, it seemed that his fingertips came up under and inside the "sphere" of my grab; somehow this popped my elbows into the air, and then at that point I was so light that the slightest flick of his hands would knock me away. There were none of the large movements we normally see, eg, torso leaning forward, or elbows dropping to get underneath them my grab. There was no feeling of ordinary muscular strength in the forearms; i've done this long enough that i can tell whether tori is deriving power from his elbows, his shoulders, his biceps, etc. It was as if at the very moment of contact, he was already underneath my center--and that was all he needed. Don't know if this helps any.
What you describe with the fingertips is very much the same sense of what I am talking about in terms of action "behind" him. It does not take much, because he is not defending that -- and cannot if he is really committed to the attack. The large movements of the body are superfluous to the kokyu at connection.
When you "get" the sense (and it is a sense, not technique), you literally "shake off" the attack while actually firming the connection -- if that makes any sense. His arm motion is a reflection of that same reciprocal motion as in tekubi furi -- like waves bouncing back off a hard surface. His arms become my arms as far as that the same instantaeous rotation/vibration/wave (all accurate physically) that occurs in tekubi furi or furitama -- the only difference in the kokyu tanden ho is that there is, at minimum, only a half-cycle of that reciprocal action, and then his center is going. The only large movement necessary is following uke in his fall to maintain the irimi in the kokyu.