Kosoto Gake (小外掛?), sometimes known as “minor outer hook", the English translation, is one of the original 40 throws of Judo as developed by Jigoro Kano. It belongs to the third group, Sankyo, of the traditional throwing list, Gokyo (no waza), of Kodokan Judo. It is also part of the current 67 Throws of Kodokan Judo. It is classified as a foot technique, Ashi-waza. It is often used as a counter-throw to tai-otoshi, after having stepped over the leg. To perform the technique, the tori situates themselves to the side of the uke and reaches around their back to grip their face or neck; the tori then moves backwards, forcing the uke off balance. The inside leg is reaped by pushing the back of the knee with the closest foot.
Although this Waza closely resembles the Kosoto-gari (Small outer reap), its advance against the opponent is deeper when performing the throw.
Tori feigns an advance against Uke, and then withdraws, pulling him forward, waiting for the moment when Uke steps forward.
When Uke pushes back against the advance, Tori feigns a retreat, but actually advances to hook the heel of Uke advancing foot.
Tori then pulls Uke in the direction of the hooked foot while also grasping Uke uniform between his shoulder and chest with his Tsurite (Lifting hand), lifting Uke to destabilize and throw him.
In combination with both his arms, Tori also places the bottom of his forward-leg foot against Uke weight-supporting leg, and then uses the spring force from the knee of his own supporting leg to throw Uke backwards in a diagonal manner.