Photo via Politeri/Flickr
Based on the photo above, you can see they do make keyboards with Japanese characters. However, according to the article Typing Japanese on 400milesnorth, it may take you 5 keystrokes to output 3 characters.
At a loss for words?
Even with my limited knowledge of the language I knew that couldn't possibly account for all the Japanese characters. Sure enough, even Sony couldn't figure out how to accomodate the language.
Photo via 1000 words, 1000 days