No, I'm not talking about Japanese supremacy.
Today, most keyboards use one of three different mechanical layouts, usually referred to as simply ISO (ISO/IEC 9995-2), ANSI (ANSI-INCITS 154-1988), and JIS (JIS X 6002-1980), referring roughly to the organizations issuing the relevant worldwide, United States, and Japanese standards, respectively. (In fact, the mechanical layouts referred such as “ISO” and “ANSI” comply to the primary recommendations in the named standards, while each of these standards in fact also allows the other way.)
JIS keyboards contain additional characters to support entry of Japanese text. With Windows keys, they are typically referred to as 109-key: they have four more keys compared to ISO, and five more keys compared to ANSI.
The purple keys illustrate the keys that differ from ANSI on a prototypical Japanese keyboard.The specific size and quantity of the Japanese input keys varies between keyboards. Common features to Japanese keyboards are the single-unit backspace, reduced width right shift with additional key (on the opposite side to where ISO adds a key beside shift) and vertical enter. The space bar is greatly reduced in width however remains to be still in centre position. In place for shorter space bar adds extra keys mainly for Japanese character inputs. These are muhenkan, henkan, and kana keys respectively.
ANSI vs JIS @ Deskthority Wiki
What does this mean?
Wider wide mod—two-column hand separation.
Thus, more accessible right-hand-side special keys.
More thumb keys.
One downside is that the exact spacebar-row layout isn't consistent across various keyboards. I have picked Topre's implementation in their current (as of early 2017) Realforce product line (i.e., 91-/108key models). The spacebar row is then 1.5-1.0-1.5-1.5-2.5-1.5-1.5-1.5-1.0-1.5.
The main-section layout, that I propose, is following:
The features are following:
Two-column hand separation.
Enter and right Shift keys adjacent to right-hand little finger.
Left-hand-controlled spacebar stretching to the right from the C/V key (i.e., in a reasonably natural position).
Spacebar-row Backspace key (accessible with minimal stretching).
Right-side-corner spacebar-row modifiers as accessible as their left-side counterparts.
A pair of extra modifiers.
Relatively large (1.5u) modifiers in general.
Escape and Delete keys in upper corners of the main section.
ISO layout's extra key.
Attached files are the layout-proposal picture, and a respective JSON configuration for Keyboard Layout Editor.
Get yourself an ergonomic keyboard. Learn Maltron. Or stenography.