How to have a Japanese desktop on your Linux/Ubuntu box?

Here is what I did in order to have an English-installed system be like a complete japanese one for specific users.

I installed all of these packages (with aptitude install):

language-pack-gnome-ja
language-pack-gnome-ja-base
language-pack-ja
language-pack-ja-base
language-pack-kde-ja
language-pack-kde-ja-base
language-support-extra-ja
language-support-fonts-ja
language-support-input-ja
language-support-ja
language-support-translations-ja
xfonts-intl-japanese
xfonts-intl-japanese-big

Some other packages will be installed due to dependencies found by aptitude.
Then, for the users who want to have their GUI all in Japanese, just put the following line in their ~/.profile file:

LANG=ja_JP.UTF-8

I use this for my Japanese learner user account, and some Japanese friends using my computer use it also in their user account and are perfectly happy with it.