Uki attacks with a two hand wrist seizure.
The one being attacked drives right hand (or left whichever side you're doing the technique to) down toward the floor, then straight up with palm facing tori as if looking into a mirror. With the opposite hand, reach under with the thumb in the back of the uki's hand, tori's four fingers inside the uki's palm. By pushing forward, tori's hand is released and placed in the back of the attacker's hand behind the knuckles, cutting toward the attacker's little toe, dropping the attacker to the floor. The person being attacked finishes the technique by pinning the attacker's arm against the knee.