Hi,
I think the locale file ja.po is corrupted (some greater than signs in english have been replaced by > in Japanese).
For example:
#: templates/viewtopicactionbuttons.tmpl:28
msgid ""
"title='Search all webs for topics that link to here' accesskey='l'>A&ll Webs"
msgstr ""
"title='\x{5168}\x{3066}\x{306e}\x{30a6}\x{30a7}\x{30d6}\x{304b}\x{3089}\x{3053}\x{3053}\x{306b}\x{30ea}\x{30f3}\x{30af}\x{3059}\x{308b}\x{30c8}\x{30d4}\x{30c3}\x{30af}\x{3092}\x{691c}\x{7d22}\x{3057}\x{307e}\x{3059}' "
"accesskey='l'>\x{5168}\x{3066}\x{306e}\x{30a6}\x{30a7}\x{30d6}"
I have replaced the > by a greater than sign in the relevant labels (around 12 strings) and it looks fine.
Regards