The free Microsoft tool "AppLocale" is designed to set the system locale for specific programs.
It does not require a reboot / restart of the operating system - and again, was written by Microsoft.
The tool's only purpose is to set the system locale for a specific program and not for the whole OS. Therefore no rebooting is required.
The tool does not require any advanced system knowledge whatsoever.
The user however needs to know which file starts the setup / game he wants to run with a different (e.g. Japanese) system locale. It is way faster than changing the whole system locale (even without the reboot).
The steps are:
1. Download AppLocale
2. Install AppLocale
3. Execute AppLocale
4. Select game setup or executable (depending on whether you wish to install the game or just run it)
5. Select the language / locale from the menu (e.g.: "Japanese" - will be displayed as "日本語").
Optional: Check checkbox "create shortcut" and enter a name for the new shortcut (e.g. "Japanese start Fate Stay Night"). The shortcut will be made in the startmenu folder "Microsoft AppLocale"
6. Click "Finish" to run the program with the specified settings.
If you have created a shorcut you can now start the program / game with the specified (e.g. Japanese) system locale simply by double clicking the shortcut as you would any other file.
Download Link:
http://www.microsoft.com/en-us/download/details.aspx?id=13209
I think this tool should be added to the FAQ section of how to set the system locale to japanese.
It works 100% as it does the same as changing the whole OS system locale does - but only for the specified program.
