NEC 日本電気 M-Type keyboard

Japan is the pioneer of thumb-key keyboards.

NEC 日本電気 Keyboard based on a then new Japanese language input system, called M-式 (M-type or M-system).

M-type is designed by Dr. Masasuke Morita at NEC in 1983.

M-type is 2 things:

1. A efficient English-Letter (romanji) based input system for inputing Japanese.
2. A physical keyboard design.

Note that the vowels {E, U, I, A, O} are all on the left hand home row. This is similar to Dvorak Keyboard Layout.

For detail about Japanese input systems, see Japanese Keyboard Layouts

More info about M-type keyboard:

[【NEC】 Keyboard based on new input system (M system) 2013-01-21 By Information Processing Society Of Japan. At http://museum.ipsj.or.jp/en/computer/word/0027.html ]

Other M-Type Designs

Over the years, there are several M-Type keyboard designs.

Here's machine translation:

Former Japanese electrical special adviser Morita Masanori M-type keyboard that Mr. devised ( '83 ~) . Vowel to the left , and remember the ease of key arrangement to place the consonants to the right , by a composite key in which you can enter the left and right alternately typing and multiple string with a single keystroke , that was realized a high-speed Japanese input . In addition to that it has been mounted on a great writer , for the PC-8801/9801, is for Windows was released

NEC M-Type Keyboard 1990

NEC M-Type Keyboard 1992