NEC 日本電気 M-Type keyboard

Japan is the pioneer of thumb-key keyboards.

M-type

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

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

Here's the translation (by Google translate)

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

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]