"Second form" or "arm-turning pin": tori leads uke over the arm twisted inwards, by applying pressure on the base of the thumb
Nikyo builds on ikkyo (first osae waza form) but differs significantly in the build-up: the principle of nikyo is based on a rather horizontal circular movement with which uke is "sucked in" before being guided to the ground via the wrist lock. Nikyo is very often chosen because uke holds the arm outstretched and therefore ikkyo is not well suited.
Essential features are the twisting and locking of the wrist via pressure on the base of the thumb and the positioning of uke's hand on the collarbone.
The nikyo wrist lock can be very unpleasant, but the effectiveness of the technique does not depend on the pain inflicted. (Besides, we respect our training partners far too much to inflict pain on them purposefully.)
The final nikyo immobilisation pin ("double-teacup" pin) is clearly different from the ikkyo pin.
Nikyo can be understood as a continuation technique applied when ikkyo does not work.
