[coldtea]

>Even if as the parent comment says China had round money previously that would not explain that, unless you can provide a line of reasoning similar to the one in the article showing how/why Korea and Japan ended up with "circle" based on that previous Chinese money the parent mentioned.

First, why wouldn't they? They borrowed terms and cultural ideas from one another all the time and have several words common. If anything, it's the theory in the article that has the burden of proof.