Train Tickets

Hi,

I'm wondering if i plan to travel on 27th december by Rail can i buy tickets on the 26th at the ticket offices . i.e can i buy tickets a day before the actual date of travel.

Thank you !

Most trains in Japan have non-reserved cars for which tickets never sell out.

In case you intend to make seat reservations, note that December 27 will not be dramatically busy. Yet, there will probably be some trains that are booked out, especially in the afternoon and evening in direction of Tokyo. So, it depends when and what train you will be riding, but generally speaking, you have rather good chances to make seat reservations, especially if you are somewhat flexible with regards to the time to travel.

The New Year rush does not start until the 29th.

is there an extra cost involved with making reservations both in person and online ?

Thank you !

It depends on what you mean by reservation.
If you mean just buying the ticket, you can buy it the day before. Like buying flight tickets, you don't have to buy on the day itself. If you want to make a reservation for a reserve seating, you would have to pay extra.
For airline this would be similar to how some airlines charge for choosing your seat (upfront, aisle, window, etc)

Summary
No charge for buying ahead of time but a charge for choosing (reserving) seat