Подождите, я на том же сайте вижу это:
CANCEL MY JRP
After purchase, it is possible to cancel your Japan Rail Pass and be refunded under certain conditions. Please find below the details of the cancellation procedure.

UNTIL WHEN CAN I CANCEL MY JAPAN RAIL PASS?
If your voucher has not been exchanged, your Japan Rail Pass can be refunded within a year from the date of purchase.
HOW DO I REQUEST A REFUND?
In order to get your Japan Rail Pass refunded, you need to send your unused voucher to our production office in London preferably by registered mail or any secured transportation way such as FedEx):
Japan Experience
22 Bloomsbury Square,
WC1A 2NS - London
UNITED KINGDOM
Once we receive your ticket, you will be reimbursed on the credit card used for the transaction, less the cancellation fee, and you will receive an email confirming the cancellation.
Note that the refund can take between 2 and 4 weeks.
HOW MUCH DOES THE CANCELLATION COSTS?
The cancellation cost is 15% of your order (excluding shipping charges).
Please note that if your voucher has already been exchanged for the Japan Rail Pass and / or you have already used it to take the train, a refund will no longer be possible.
https://m.japan-rail-pass.com/mobile/common-questions/how-to-cancel-my-japan-rail-pass