This is a good question. I have seen a wide variety over the years from native Japanese speakers. Some use the 1990s-style kana keyboard. Some use romaji input where real-time software (called an IME) automatically suggests conversion to the final Japanese word (katakana/hiragana/kanji, etc.). On a mobile phone there is usually an option to do 1990s feature phone style kana input, where the 12 key input is shown, and you press one key as many times as necessary to rotate to the correct kana that you wish to input. You can see young girls with frighteningly long fingers nails jamming away -- chatting with their friends via mobile text (Line, SMS, etc.). Their "touch memory" (and sensitivity) must be jaw-droppingly good -- like a professional drummer or something similar.

Native Cantonese speakers in Hongkong have similarly diverse input methods. I've even seen tiny digital draw pads at the public library. It is pretty exciting (to me!) to watch an elderly person furiously scribbling away on the pad, inputting traditional Chinese charaters to search something on the Internet or in the media catalog. I think it is very cool that public library makes a strong effort to empower all types of users.