I wrote an article about Debian locale configuration at Debian Locale Configuration - 20180613 - Shammerism, this is based on LANG=C.
Here is a procedure how to configure Japanese locale.
- Edit /etc/locale.gen and remove comment of the line which you want to use
- Exec locale-gen
- export LANG=$LOCALE_YOU_WANT_TO_USE
- export LC_ALL=$LANG
- locale-gen --purge $LANG
- dpkg-reconfigure -f noninteractive locales
- update-locale LANG=$LANG LC_ALL=$LANG
- perl -v