Green car for single journey?

Hi

I know the questions regarding JR Ordinary vs Green car have been debated endless. This questions is different!

If we buy an ordinary JR pass can we upgrade for a single journey? We are travelling from Tokyo - Kyoto over the busy New Year period and want to travel in Green car to beat the crowds. For the rest of the time (14 days), we are happy with the ordinary car!

Is it possible to upgrade for the journey? How much would it cost? I am trying to work out if this is cheaper than upgrading for the entire 14days!

Thanks
MR

It is possible, but you have to pay more than just the green car supplement. Namely, you will also have to pay the limited express fee.

Tokyo-Kyoto would cost you a supplement of around 10,000 Yen per person.

During the New Year period, traffic is horrible on only a few selected days and directions. This year, December 29 in direction out of Tokyo can be expected to be the peak. Not sure about the peak of the "return-rush". I guess it will be distributed over January 2, 3, 5 and 6 will not be so extreme.

Please note that trying to get a green car doesn't necessarily increase your odds of getting a seat, only booking early in advance does. During peak travel season and on the peak travel days of that season all train cars sell out , doesn't matter if it is green or ordinary, reserved or unreserved, trains will travel at overcapacity.