Aikido in 3D

Ryotedori Kokyunage Sokumen

Yoshigasaki Sensei demonstrates here how the technique can be executed in two dimensions: downwards, upwards, and sideways. This all occurs along a single plane of space, i.e., in two dimensions.
By leading Uke with his arms slightly backwards, he adds another direction.
So, we now have three dimensions.
Yoshigasaki Sensei explains that one reason for this form is that Uke has difficulty falling in the two-dimensional version. In the three-dimensional version, Uke is turned so that, ideally, his legs interlock and thus she automatically falls to the ground.

The exercise

If your feet stay in place and your torso is twisted, your legs will cross and you'll automatically land on your buttocks.

This is not only a mobility and balance exercise for adults, but also a fun exercise for children's training.

Partner exercise

In this "falling exercise," a partner can provide a little assistance by pushing on the shoulders.
The exercise then ends in the koho tento form.

Various Forms

The video shows three examples from the years 2000, 2009, and 2019.
In Tsuzukiwaza 4 Ryotedori, the technique is performed once with firm contact and then in a flowing movement.

The turning form for Uke shown above can only be performed with firm contact. If Uke is guided by Ki and without body contact, an additional turning movement would only create unnecessary collisions and might even result in unphysiological movements for Nage.

Other schools

In more traditional Aikido schools, this technique is called Iriminage sokumen. In Ki Aikido, Iriminage became Kokyunage. The older forms are more direct (irimi).

The French Aikido teacher in the Tissier style moves directly into Uke and practically slams him to the ground.
The Aikido teacher in New Zealand uses his hips together with his arms; this is more Saito style.
Source: YouTube