If you're looking for an alternative to CMU Sphinx that's still FOSS, you really should check Julius out. There are plenty of docs on getting it running with languages other than Japanese. If you're curious about how well it can work, check out this[2] demo (requires Chrome).
It seems like this demo is not using Julius, but it's mixing messages a bit. The bottom of the page says "Service provided by Google Inc.", but the link right next to it (for downloadable software, also apparently called "kiku"?) says Julius etc.
[2] http://www.workinprogress.ca/KIKU/dictation.php
It seems like this demo is not using Julius, but it's mixing messages a bit. The bottom of the page says "Service provided by Google Inc.", but the link right next to it (for downloadable software, also apparently called "kiku"?) says Julius etc.