For the installation of Japanese Language support, you may need the install disks of your operation system (or your browser).
Windows users also have a more complete solution which is to install the language support: Windows Update from Microsoft.
This brings in the Japanese Language Support and Japanese Input Method Editor which allow users to view and input Japanese with reasonable ease. The IME works with MS-IE and from V4.72 also works with Netscape.(Note that even if you have no intention of using IE, you may need to have it installed in order to be able to install the IME.) Later versions of Windows based on NT (2000, XP) come with fonts and an IME already.