LANG=ja_JP.UTF-8

$ perl 
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
        LANGUAGE = (unset),
        LC_ALL = "ja_JP.UTF-8",
        LANG = "ja_JP.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").

$ export LC_ALL=ja_JP.UTF-8
-bash: warning: setlocale: LC_ALL: cannot change locale (ja_JP.UTF-8)

ロケールが無いやつだこれ

# apt-get install locales
# dpkg-reconfigure locales

ja_JP.UTF-8 だけ有効にして完了