“Hips rotation”

Famous principle of “hips rotation” (KOSHI-NO-KAITEN – 腰の回転; waist rotation) might be demonstrated with a help of a traditional Okinawan musical instrument, DENDEN DAIKO (でんでん太鼓), the drum. . 

In order to rotate the hips/waist (the core of the body)  linear simultaneous  movements back and one forward are produced as shown on the image above, resulting in the rotation of the drum handle, with analogy to the DENDEN DAIKO (でんでん太鼓).

Fans of Karate Kid movie may recognize recognize this instrument too.