When I install Windows on my Mac with VMWareFusion, for some reason, it recognizes that I have connected an English keyboard, even though I have connected a Japanese keyboard. There are many solutions to this problem, but there are many cases where it doesn't work, and I struggled with it.
I installed the following tool and selected a Japanese keyboard and it worked. It seems to be compatible with Windows XP, Windows Vista, and Windows 7.
Keyboard Switching Tool Ver1.1 (2009/8/18)
English 
Japanese