For those who want to visit different parts of the country, the JR railway network offers, only to foreign tourists with the status of “temporary visitor”, the Japan Rail Pass (JR Pass).
The JR Pass allows travelers to have unlimited travels on JR lines, buses and affiliated ferries, and can only be purchased outside of Japan. It is valid for 7, 14 or 21 consecutive days. 
What about children? Children aged until 5 do not pay for the train (or subway) ticket if they sit on their parents’ lap. For children aged 6 to 11, the JRP costs half the price.
How does it work? Once purchased, a voucher is shipped to your house: in Japan, it must be converted to the actual pass within three months from the issue date. The easiest thing to do is going to one of the airport offices to fill in the appropriate forms, where the issue date will be indicated.
With a Japan Rail Pass, you can use all the means of Japan Railways, including the shinkansen (bullet trains), except for two shinkansen lines: Nozomi and Mizhuo.
The following are also included:
- the urban railways, therefore including JR Yamanote Line, and the Tokyo Chuo/Sobu Line;
- the JR shuttle bus, from and to the airport;
- Narita Express to Narita, the main airport of Tokyo;
- Monorail train to Haneda;
- Haruka train to Kansai (Osaka);
- the JR ferry from Hiroshima to Miyajima and vice versa.
- Some JR local bus lines are also available for free.
Here you will find all the information you need. (http://www.japanrailpass.net/en/index.html)
