I've gone thru my stash of unused postcards. All I could find for Japan were replicas of well known paintings or water colors. Two are of Kyoto gardens; the others are mountains and rivers. I can understand that this might not be what you want; if you'd like them, PM me with your address.

Here's a thought: if we have photos of these places, you could get the card that sticks on them to make them into postcards. The ones that I have are called PhotoPostos.