LANG - How to Configure LANG in Linux

$ echo $LANG

$ locale
LANG=ja_JP.UTF-8
LC_CTYPE="ja_JP.UTF-8"
LC_NUMERIC="ja_JP.UTF-8"
LC_TIME="ja_JP.UTF-8"
LC_COLLATE="ja_JP.UTF-8"
LC_MONETARY="ja_JP.UTF-8"
LC_MESSAGES="ja_JP.UTF-8"
LC_PAPER="ja_JP.UTF-8"
LC_NAME="ja_JP.UTF-8"
LC_ADDRESS="ja_JP.UTF-8"
LC_TELEPHONE="ja_JP.UTF-8"
LC_MEASUREMENT="ja_JP.UTF-8"
LC_IDENTIFICATION="ja_JP.UTF-8"
LC_ALL=

$ locale -a | grep -Ei "ja|jp"
ja_JP
ja_JP.eucjp
ja_JP.ujis
ja_JP.utf8
japanese
japanese.euc

export LANG=ja_JP.UTF-8

LANG=en_US.utf8

LANG="ja_JP.UTF-8"
SUPPORTED="ja_JP.UTF-8:ja_JP:ja"
SYSFONT="lat0-sun16"
SYSFONTACM="8859-15"

LANG="ja_JP.eucJP"
SUPPORTED="ja_JP.eucJP:ja_JP:ja"
SYSFONT="lat0-sun16"
SYSFONTACM="8859-15"