Japanese support works, just download the plugin from within the app.
The Japanese font that comes with the Pandora is poor. It's missing a lot of kanji and shows a lot of the kanji it does have in the Chinese style. If you use kanji in your deck, you really ought to download a better font.
To add a font to the Pandora, download a TrueType (.ttf) font and add it to /usr/share/fonts/truetype/ Yes, this is on your NAND if you aren't booting from SDCard. I haven't figured out a way to get anki to search for fonts inside appdata yet. Anyway, quality
Japanese unicode fonts are freely and legally available here.
My favorite among that bunch is EPSON 教科書体 (epkyouka.ttf, "Epson Textbook"). This font is very good for those studying how to write characters because it shows them how they are properly written, not like a block font you'd get out of a computer. It also scales down to small sizes extremely well and is the easiest to read Japanese font I've encountered for kanji. It's available from that site (via epson.jp), but it comes in a self extracting .exe so I rehosted it
here (4MB download)
After you add a Japanese font to your /usr/share/fonts/truetype/ folder, you can make anki use it using the settings -> Fonts and Colors menu.