Download link: last updated on May 13, 2014 at 06:53 AM JST (UTC+9).
I'm currently working on improving the translation.
Japanese language file is available on a git repository now.
Contributors
Please view the commit history. I translated all files from scratch.
Language files received many updates based on feedback. Thanks the Japanese community!
A message to developers:
If you need a Japanese font, I think M+ font is a solid option. This is free software (not freeware). Please refer to the font license. Outline fonts contain about 3000 most-used characters, and bitmap fonts contain about 7000 most-used characters.