I'm sorry ikeyPikey but you're quite wrong about Chinese and Japanese. The great majority of characters used in Japanese have identical or very similar meanings to those of the Chinese characters.
To take a very simple example, the inscription on the Chinese stamp above would be perfectly intelligible to a Japanese-speaker, making allowances for the simplified form of the fifth character:

means exactly the same in Japanese as it does in Chinese.
The first character in the word for 'China'

is certainly helpful in identifying Chinese stamps. However, it's also a common Japanese character, having exactly the same meaning as in Chinese. It's one of the characters Japanese school children learn in their first year at school.
Just beware of it in postmarks. For example, just about every large Japanese has a 'Central'

Ward. And the 'Central' is also perfectly intelligible, as 'central', in Chinese.