Originally Posted by
freecia
I have. Once. I took a commuter express to Koganei in Tochigi which is a "local" train (regular base fare with window bench seats) + 1 double decker Green car with reserved seating fee if you don't want to be mashed up into an armpit during commute hours. The ticketing agent looked at me a bit funny because it is a regular ticket but I thought it was a Ltd Exp or Rapid seeing as there's a green car and it takes 1 hr 20 min from Ueno. He still sold me the ticket and I paid with a credit card. So there you go

It is possible.
Went to Koga on Toholu Line, these days called Utsunomiya Line, for work. But tickets at manned ticket counter so I can used company issued AmEx car for expense, so I knew that, nothing I did not know, I always do that.
I was talking about using credit card at manned ticket windows at Shinjuku to but 200 yen ticket to Shinagawa, I was talking about buying ticket for 国電 using credit card, if you are old enough to know this terminology.