Tani otoshi is one of the original 40 throws of Judo as developed by Kano Jigoro. It belongs to the fourth group of the traditional throwing list in the Gokyo no waza of the Kodokan Judo. It is also part of the current 67 Throws of Kodokan Judo. It is classified as a side sacrifice technique.
Tani Otoshi – Valley Drop In Action
From migi shizentai, it may happen that when you try to break Uke’s balance toward his right front corner (migi mae sumi), he may oppose this move by withdrawing his right leg. Taking advantage of his withdrawing movement, break his balance towards his right rear corner (migi ushiro sumi) and step forward with your left foot. The pull toward Uke’s front must be strong and powerful enough so that Uke strongly resists to his rear.
As Uke resists your pull, step quickly toward Uke’s rear with your right foot slide stepping so that you’re able to place your right leg across the length of Uke’s heels from behind. Place your left hand on Uke’s chest while maintaining your grasp of Uke’s left sleeve with your right.
You should now be seated to Uke’s left with your right leg stretched out behind and touching both ankles and your left leg bent to drive Uke backwards.
With your hands working in unison, drive with your left leg directly to Uke’s rear (ma ushiro) while pulling down hard on the sleeve and driving your left hand through the chest to the mat.
Note: It is OK for Uke’s butt to strike the mat first so long as you continue to drive the chest to the mat. If his back and shoulders hit the mat with force, you will still earn Ippon. The drive is critical to this technique working.