. . . nage's hand wraps the forearm from the inside in a vertical nikyo/sankyo hybrid (twisting the arm/qua open rather than closed) it still locks the elbow and shoulder and ends in a sumi otoshi-esque throw. Again, upon reflection, many would argue this is not even remotely related to nikyo due to the opposite direction of rotation (probably has it's own name), but I see some common principles; then again that is just my take.
Thank you for clarifying! It would be interesting to see what the lock you intended to describe looks like, even if you can't exactly replicate the effect (at least at this time).