There is considerable internationalization work going on
in Perl. People like Jeffrey Friedl have been using Perl
to process Japanese text for some time, so it is possible
even if I haven't done it.
An alternative to consider if you don't want to figure out
the appropriate hoops for Perl to jump is Ruby. It was
developed in Japan so I bet its support for working with
Japanese text is pretty good. I would have to investigate,
but I suspect that Perl's Unicode support is further
along. But Ruby has natively supported common Japanese
formats for a while, but Perl isn't quite so strong there.