javac doesn't work in ja locale on Solaris at all.
It displays an error message which means "Unsupported encoding: eucJP-open".
(Because the actual message is displayed in Japanese, I translated it to English
for convenience. The original English message may be different from the above one.)

I have some Japanese locales installed on my Solaris8. javac works as expected
in ja_JP.PCK or ja_JP.UTF-8 locale. javac seems to cause an error only in
locales which use EUC_JP encoding.

Because I didn't know which subcategory is appropriate for this bug
and java(runtime) works as expected in ja locale unlike javac, I assigned
this bug to compiler for the moment.