Languages like Japanese and Chinese are more different from English (the language most Nim resources are in) than other languages Nim users tend to speak, so they warrant their own resources more. Otherwise relative to population I don't think there's an exceptional amount of users from anywhere in Asia
What's weird is there aren't many North American users. Other languages can be tied to American companies and so they might not receive much adoption in Europe/Asia, whereas it might be that Nim doesn't have this problem.
Not necessarily popular, it is a self-public book like the Amazon one.
https://plausible.io/nim-lang.org shows some insights regarding where the visitors are from.