Nikkyō literally translates as “second teaching,” because its the second joint lock taught in aikidō. Within Goshin-Jutsu, it is referred to as reverse wristlock, since it is the complement to kote-gaeshi.
The basic premise is that the defender grabs the opponent’s wrist and rotates it to the inside, to the end of its range of motion. Further rotation rotates the elbow and shoulder, locking them as well. If the opponent resists, they will place additional torque on their wrist, increasing its chances of breakage, with possible collateral damage to their elbow, shoulder and their associated ligaments. If the opponent yields to the lock, they are forced to bend at the waist, which is an excellent setup for a knee kick or downward elbow strike.
[Reverse wristlock, fast and slow, for different angles.]
If the opponent bends their elbow, they will isolate and unnaturally further stretch their forearm ligaments. The only way for an opponent can alleviate the pressure of this "Z-lock" (or N-lock) is to fall to their knees and straighten their arm out, which sets up knee kicks, stomp kicks, or the shovel pin.
To setup a Z-lock:
- Opposite-side grab the opponent’s wrist, twisting it so that their thumb is down and their fingers are pointed at your same-side shoulder.
- Pin their wrist against your same-side collarbone.
- Use your same-side hand to hook the inside of the opponent’s elbow, to force their arm to bend.
When the setup is complete, it should look like the image below:
[Z-lock setup from sever angles, ideally from above as well.]
- Bow to the opponent’s centerline to apply the lock.
[Z-lock, fast and slow, for different angles.]