I don't know the answer! But have you activated your japanese fonts with font book & System prefs-international & listed japanese? I suspect you'd need to have japanese activated for java & LW to be able to utilise these characters. You 'might' need to have Japanese pushed to the top of the list. Likewise I have a couple of asian language fonts activated for web purposes & general. I've never attempted to apply them to LW so I don't know.

I was thinking a sure way to do it should be to change your system language settings to japanese. But then that's also related to the interntional prefs. Once you've set up options, you can switch over quickly using the menu bar at top right where the national flag shows.