"Corner drop": tori influences uke's center in a way that makes uke tip over one side.
This throw is usually applied to the attack (gyaku-hanmi) katate-dori.
Tori touches uke's crook of the elbow and moves sideways to the dead spot behind uke, shifting uke's center with a spiralling movement so that he tips over to the side. Tori often kneels down to increase the effect and avoid uke's fist.
Search "Basic Forms" page for videos showing SUMI-OTOSHI
