"This keyboard has been used by stenographers who make captions for news. There are 10 keys; 5 keys on the right (vowel) and 5 keys on the left (consonant). You don't have to move your finger up-and-down like when you use regular keyboard. Once you get used to this keyboard, you can type more than 300 letters per minutes. Plus able to type 2 letters at the same time.
"a"+ "i" → "ai"
"aru" + "mashita" → "arimashita"
There are many more shortcut keys."