一 The Left Chest and Left Upper Back
二 The Right Chest and Right Upper Back
三 The Left Abdomen and the Left Central to Lower Back
四 The Right Abdomen and Right Central to Lower Back
五 Frontal Lower Abdomen
六 Central Lower Back
Before I go on, please note that this is my simplification: While there are some small variations—description-wise (amongst the senior Shotokan instructors here in Japan)—I designed the above simplified list for my ‘English-only-speaking’ deshi (students) and renshusei (trainees). In addition to this, I’ve avoided using the medical/anatomical terms for body parts. My rationale behind this was, and is, to optimally clarify this imperative breakdown; moreover and more importantly, to physically understand/apply this knowledge. With this in mind, I’d like to explain how the six parts/sections of the trunk are used.
overarching categories: 1. 縦 (Vertical); 2. 横 (Horizontal--forward and back); 3. 丸 (circular on an even plain); 4. 円 (like a 'ball').