Train Reservation

I am coming to Japan during the last week of December, until the first week of January, which is the busiest period for travelling In Japan. I am therefore very worry that the J R Pass that I bought overseas will not help much since I cannot start Train Reservation from overseas. By the time I reach Japan just before Xmas, most of the Train Seats will be gone. Please advise how I can make advance reservation of Train Seat from overseas. For your information, only after the Train is confirmed, I can proceed to book Hotel. So my Hotel is also not booked until I can be sure I have the Train Tickets. So I need your help in this matter, thank you.

Your JR Rail Pass is your train ticket. You may enter any JR train, even if all seats of the reserved seat cars are all booked. All shinkansen, ( but two lines to the north ) have non-reserved cars, too. You just queue at the station and you take the next free seat or in very worst case stand till the next station when some passengers will depart and seats become free. Not all days between Christmas ( no holiday in Japan ) and the days after New Year will be peak travel times. You can book all your seat reservations immediately after arrival in Japan and exchange of your Exchange Voucher to the JR Rail Pass. I see no problems for you to get free seats. Start booking your accommodations now.