I've just finished writing a Japanese application in FoxPro. It can be done but there are a lot of problems, pitfalls, and limitations.
Sort order, fonts, unicode, IME Editor, etc. Sort order is definetly the most difficult. FoxPro doesn't sort the Japanese language the way Japanese people do and Hiragana, Katakana, and Kanji most be intermixed in order for it to be useful.
The fonts are just flat out odd (characters will appear on the screen turned 90 degrees with some fonts). Even something as simple as reading e-mails from Japan becomes a chore due to the limited character set of most e-mail programs.
If you need a lot of info, e-mail me (twenger@thomcomp.com).

* WARNING: Writing applications in Japanese has been known headaches, sleeplessness, and stomache irritations in test subjects and can be hazardous to your health and mental well being.

Tom