Japan Rail Pass is a special train ticket for foreign tourists.
This Web site explains who is eligible for this ticket, and how and where you can purchase it.

The ticket is valid for all JR trains including Shinkansen Express (bullet trains), except for Nozomi trains. In spite of the name "Rail" Pass, you can also use it for JR bus and ferry. Please refer to http://www.japanrailpass.net/eng/en004.html for more details.

The pricing can be found at http://www.japanrailpass.net/eng/en003.html