I purchased the Rail Pass via a London based travel agency. The process was smooth and direct as I opted to collect the pass personally. It was neatly wrapped with receipt and additional promotional ads. I had the option of seven or fourteen days duration. I needed nine so with a bit of creative thinking I managed to fit in this seven day pass into my very busy itinerary. The main aim of it was to get me as north as possible. Saporro was the last stop where you could use the Pass. From there northwards you either have to take a bus or a local commuter train if you plan on continuing your journey to the Wakkanai, Monbetsu or Cape Nosappu (Easternmost point of Japan).
What is important on entering the country one needs to ensure the right visitor visa is stamped at the border. Then the Pass voucher needs to be validated in one of the authorising points across Japan. In my case, it was in Fukuoka train station soon after I landed in Fukuoka airport, flying from Naha, Okinawa. I had to take a quick and short train journey from the airport to the railway station. Once I have had my Rail Pass validated there I started using it freely across the Japanese islands.
Below is the official info about RAIL PASS in general.
JAPAN RAIL PASS, a joint offering of the six companies comprising the Japan Railways Group (JR Group), is the most economical means of traveling throughout Japan by rail. There are some restrictions on use; for example, it cannot be used for travel on NOZOMI and MIZUHO trains on the Tokaido, Sanyo, and Kyushu Shinkansen lines. Even if you visit Japan with an Exchange Order, to be turned in for a JAPAN RAIL PASS, the exchange cannot be made unless you have “Temporary Visitor” status; if you enter Japan under any other official status, such as “Trainee,” “Entertainer,” or “Reentry Permit,” you cannot change the Exchange Order for a JAPAN RAIL PASS. Please note that according to a strict interpretation of the Japanese Immigration Law, “Temporary Visitor” status differs even from other types of stays that are also for only short time periods.