Seoi-Otoshi (hand technique)

Seoi-otoshi is accomplished by making your opponent off balance by pulling in a straight forward motion or a right forward motion. Then, pick up Uke's body on your back and continue pulling to throw over the shoulder as you drop your one knee or both knees on to the mat.

(Type 1) Drop one knee on the mat, pull Uke straight down, then throw over the shoulder (Seoi-otoshi)

Tori and Uke hold each other in right handed posture.Tori pulls Uke straight forward to make him off balance while stepping back slightly with the right foot, then place the same foot in front of Uke's right foot. Tori bends both knee and uses the tip of his right foot to spin left while he places his right arm under the Uke's right arm pit. He, then, pulls Uke's right arm and lock it against Uke's chest. Then, Uke is lifted up in the Ippon-seoi-nage position .Tori stretches his right leg to the inside of Uke's right foot and gradually lowers his body and places his right knee on the mat.
Then the throw is completed by pulling both hands straight down at once and throwing (picture 1).

In Koshiki-no-kata, Ura Number 6 Yuki-ore is similar to this technique. When Uke tries to hold the Tori from behind, Tori drops his right knee on the mat and throws the Uke over the shoulder.

picture 1

Techniques of practical applications
Tori takes the Ippon-seoi-nage position, then, places his leg against the outside of Uke's right leg. He, then, drops his right knee and throws over the shoulder (picture 2).

picture 2

Tori, from the Morote-seoi-nage position steps his right leg inside (or outside) of Uke's right leg. He, then, drops his right knee on the mat and throws (picture 3,4).

picture 3
picture 4

(Type 2) Drop both knees on the mat, pull Uke straight down, then throw over the shoulder (Seoi-otoshi)

Tori pulls the Uke straight forward to make him off balance, then, quickly steps into the Morote-seoi-nage position. At the same time, Tori drops both knees on to the mat and throw straight over the shoulder (picture 5).

picture 5

Techniques of practical application
Tori drops both knees on to the mat, then, throws from the Ippon-seoi-nage positon (picture 6).

picture 6

(Type 3) Difference between Seoi-otoshi and Seoi-nage

These two techniques are alike, especially in the lifting position. However, the difference is in the throwing concept.
Seoi-nage : lift up the opponent and throw
Seoi-otoshi : pull down and throw (at this time, one knee or both knees must touch on the mat)
Although the knee or knees touch the mat at one time during the process of the throw, if at the actual execution of the throw, the knee or knees are not touching, the throw is considered to be Seoi-nage.

It is very difficult to define these techniques in the split second of execution. It is necessary to segregate these techniques.