Comment 20 for bug 36761

agrueneberg and Benedikt's problem is due to embedded bitmap not disabled. Using 'sudo fontconfig-voodoo -l ja_JP' or 'sudo ln -s /etc/fonts/conf.avail/69-language-selector-ja-jp.conf -t /etc/fonts/conf.d/' will remedy it.

In Sancho's case, it seems the default is to select a chinese font (Kaiti?) which is higher in preference according to 40-nonlatin.conf, while when using ja_JP.UTF-8 locale, it seems to use FreeSans (if I'm not mistaken, FreeSans would give that horrible Han typeface). He should also do the solution above, and install better fonts (Takao/IPA fonts recommended).

By the way, even with the voodoo, DejaVu fonts are prepended to each serif/sans-serif/monospace list, so they will be used for Latin fonts, basic or extended. Only when it fails to find the glyph in the DejaVu series (i.e. the Chinese/Japanese fonts) will it start looking up the other fonts.

Okay so what is the issue here? Do you want this voodoo to be enabled by default? Well, seeing it's supposed to match "lang=ja" only, that can be considered.