I just created an account and played around with it for a few minutes. It appears to work with Japanese fonts, so that's a plus.
I created a math quiz and that was kind of helpful too, but it didn't seem to offer the option of mixing basic math functions. You could only get addition, multiplication, subtraction, or division, but not with them interleaved. That might just be me not figuring out how to make things correctly yet though.
I won't have much more time to work on it today, but I'm curious to see what we can do with this. The fact that it has a Moodle plugin is awesome.