I would suggest looking in Regional and Language Options in the Control Panel. You should be able to find what you need here.
Here are some suggestions:
On the Languages tab you should click on the Details... button in "Text services and input languages" to specify a keyboard setup for Japanese. This is only for typing in Japanese text. You will be able to switch between the English keyboard and the Japanese keyboard.
I would assume that you should check the "Install files for East Asian languages" checkbox.
Also on the Advanced tab check the Code pages that you will need for Japanese (go through the whole list because there are more than one for Japanese). This should allow you to read the Japanese characters.