Running nightly build from l10n which has JConsoleResources_ja.class,
jconsole is still comming in English.

Bundle: /net/disk1.sfbay/space0/crosscharge/j2se/1.5/ws/nightly/tiger_l10n_re/control/build/04-10-04/solaris-sparc/bundles/j2sdk-1_5_0-beta2-bin-l10n-nightly-solaris-sparc-10_apr_2004.sh

% jar tvf j2sdk1.5.0/lib/jconsole.jar | grep JConsoleResources
  7583 Sat Apr 10 04:50:00 JST 2004 sun/tools/jconsole/resources/JConsoleResources.class
  7589 Sat Apr 10 04:50:00 JST 2004 sun/tools/jconsole/resources/JConsoleResources_ja.class
%
% locale
LANG=ja
LC_CTYPE="ja"
LC_NUMERIC="ja"
LC_TIME="ja"
LC_COLLATE="ja"
LC_MONETARY="ja"
LC_MESSAGES="ja"
LC_ALL=
%