The Tani-otoshi (Valley drop) Waza consists of scooping up the opponent's foot and throwing him down on his back.
The Tani-otoshi (Valley drop) Waza is a Sute mi waza (Sacrifice techniques) in which a combatant falls together with his opponent, and uses the force of the fall to throw him.
Although this Waza resembles the Yoko-otoshi (Side drop) Waza, that Waza is performed from directly in front of the opponent, with the opponent being thrown laterally, whereas the Tani-otoshi (Valley drop) Waza is performed from the side, with the opponent being thrown down in the back corner.
Tori (Player executing technique) moves around to Uke (Player receiving opponent’s attack) Tsurite (Lifting hand) side, then uses his own Hiki-te (Pulling hand) to pull Uke Tsurite (Lifting hand) downward. Tori then bends his knees to lower his hips while destabilizing Uke toward Uke Tsurite (Lifting hand) side. At the same time, Tori scoops up Uke foot from behind with his Hiki-te (Pulling hand) side foot, and throws Uke down in the back corner.
The Tani-otoshi (Valley drop) can be executed in a number of different ways, such as by striking the opponent's foot with your foot in order to topple him, or by pulling his foot forward from behind, etc. The latter method (pulling the foot) is executed by slipping your arm (the arm used to hold his Tsurite [Lifting hand]) between his legs while also submarining in behind him to topple him backwards onto his back.