If you have relatives or friends coming to Japan and they plan to be the most of their time here city hopping around, it sounds like a Japan Rail Pass can be an incredible money-saver. Shiira at Gisuru.com has written THREE in-depth articles about the Japan Rail Pass, so you should go read through them carefully:

Introduction to the Japan Rail Pass

Deeper explanation of the Japan Rail Pass

and the step-by-step guide to purchasing the JRP

Basic points to bear in mind: you need to buy BEFORE you come to Japan and it’s only valid for temporary Visas; and it DOES cover Shinkansen “bullet trains” but not the super-super-super fast Nozomi; and it only covers JR trains and buses (not city subways or other companies). I’d say it’s more than worth it certainly if you plan to travel to more than a few cities here – the bullet train tickets alone cost a fortune. If you’re only planning to stay in one city though, especially Kyoto which doesn’t actually have any internal JR lines, you might want to really sit down and do the math.

Thanks again to Shiira for answering my questions about the Japan Rail Pass in such length!