[Chacal]

My mate got back to me with a little more information, the locations agree with those John's friends gave.

Here is his message:

"I am sure this is from Japan because the green letters above say 「郵便はがき」（"postal card"）in Japanese. You should read the letters on the card from the right to the left. And the price of the stamp is 0.015 yen.

Unfortunately I could not tell the details of the postmarks (red circles with dates and pictures). The left one says Gunma（群馬）prefecture and the right is from Nagano（長野）prefecture.
Each of the mark has more letters but unfortunately I could not read them all.

I guess the postmark on the right card was stamped at a post office on/near mountains in Nagano. It seems like a climbing memorabilium. There are post offices on the top of some high mountains in Japan like Mt. FUji and such offices offer special postmark for climbers. I guess the right postmark is one of them."

Hope this helps - it's interesting to find out what they are, but also that Japanese has changed so much that a native speaker has difficulty in deciphering it. That said, presumably postmarks in Japan, as elsewhere, have an abbreviated version of the location which would be difficult for all but someone in the know to read.

Graham