NS doesn't provice receipts. You can use the tickets themselves for declaration purposes.

Welcome to our NS Community, Encheng. Tochjo is correct. All the data on the e-ticket is enough to declare with, so we don't provide an extra receipt or invoice.

That’s weird. How do I use my e-tickets in my tax report? I can’t print them, can I? I can only see them on my screen, I can’t send them to the tax office.

Sure you can print them. You should get an email when you've ordered a ticket with a link to a pdf file. If you didn't, contact customer service and have them send it to you.

Note that in general you don't need to send tickets to the tax office. Only if they explicitly ask you to show proof you need to do so.