The language pack feature in Vista is ONLY available for Windows Vista Ultimate. First, be sure to upgrade Windows Vista to Ultimate if you have not done so (Im assuming that you have Windows Vista Home Premium for the majority of computers run it). Then, in Windows Vista Ultimate, you must open Windows Update (search for it in quick-search). Click show available updates and choose the Japanese language pack.
Another option is to:
1) click Start
2) click "Control Panel"
3) click "Clock, Language and Region"
4) click "Regional and Language options"
5) click on the tab "keyboards and languages"
6) click "install / uninstall languages"
The rest is self-explanatory
I have been faced with this situation before.
However, I did not get any language packs for I did not have Vista Ultimate.
Instead, I just bought a copy of Japanese Windows and installed it alongside with my English Vista.
The-Magic-Of-Making-Up-Review
Another option is to:
1) click Start
2) click "Control Panel"
3) click "Clock, Language and Region"
4) click "Regional and Language options"
5) click on the tab "keyboards and languages"
6) click "install / uninstall languages"
The rest is self-explanatory
I have been faced with this situation before.
However, I did not get any language packs for I did not have Vista Ultimate.
Instead, I just bought a copy of Japanese Windows and installed it alongside with my English Vista.
The-Magic-Of-Making-Up-Review