I think he means to emulate the locale, which really isn't a question of best more than it is a question of what works. The answer is it depends on what operating system you run, such as whether you run Windows 10 or Windows 7. If you run Windows 10, most won't work, the only two I know that will, NTLEA and Locale Emulator, don't run very smoothly. In truth, your best bet is to actually switch to the Japanese locale. Windows 7 and before have the trusty, old ApplLocale, which is actually pretty good, but WILL NOT work on Windows systems newer than 7 to my knowledge.