第二教 · Dai Nikyo
Koshi Guruma 腰車
Hip Wheel
Mechanic
Tori wraps an arm around uke's head and neck, plants the hips deep across uke's waist, and pulls the head around. Uke's whole body wheels around the hip like a rim around an axle and lands flat on the far side.
Analogy
A kid folds over a low playground high-bar at the waist, and a friend gives the shoulders a pull. The bar stays put while the whole body wheels around it in one smooth circle, feet chasing head all the way over.
Why it maps
The fixed bar at the waist is the hip serving as an axle, and pulling the head/shoulders around it is exactly the wheel-spoke rotation that carries uke over.