- O'Sensei aligns his feet on a line forming a right angle with the line connecting the feet of uke.
- O'Sensei draws uke across his hips, extending uke, rather than wrapping him in and around, bringing his hips into contact with uke's abdomen, and forming the signature cross (juji) with their bodies.
- O'Sensei positions his hips below uke's center of mass by slightly widening his stance, rather than maintaining his feet approximately a shoulder's width apart and bending his knees. It is important to remember O'Sensei was relatively short in stature, compared to his peers, and his approach would not require an extreme widening of his stance.
- O'Sensei maintains the extension, rotates his body, using his hips as a fulcrum, with his arms extended at nearly right angles to his torso to transfer the rotation, throwing uke with a seesawing motion.
Morihiro Saito Sensei reinforces these points when quoting the following instruction from O'Sensei regarding Koshi Nage, "Step forward and position your right foot between your partner's feet. Extend your left arm diagonally upward with feeling of pointing at the top corner of the wall and bring your partner's stomach onto the small of your back in such a way that your two bodies form a cross."
The overall effect of O'Sensei's technique is a hip throw exploiting the action of uke and gravity, resulting in little or no energy expenditure by nage. Saito Sensei confirms the minimal expenditure of energy by nage in the following comment, "The founder once said jokingly that there were no better techniques than Koshi Nage and that he never got tired even if he practiced them from morning to night."
Among the images used to identify the characteristics of O'Sensei's Koshi Nage were photographs of O'Sensei performing Koshi Nage found in the series of photographs known as the "Noma Dojo Techniques."
Is O'Sensei's Koshi Nage his creation or did O'Sensei assimilate the Koshi Nage from one of the predecessor arts he studied?
The complete original post by John Driscoll Sensei at: Of Oak Leaves, Blind Hogs, and an Acorn.