Strange! The same user is allowed to create accounts on the sister site of Betpanda which they have actually created for Japan. I'm wondering why they have created a new site for the people of Japan while Japan isn’t listed as the restricted country in Betpanda.io. Both sites have the same gambling license. The difference is only in the language of the websites.
Gambling and its legal status in Japan is mostly banned in Japan [1].
[1]
https://en.wikipedia.org/wiki/Gambling_in_JapanI am not a Japanese and I don't live in Japan so it's only information from Wiki. If gambling is not legal in Japan, and if Betpanda wants to provide their services to Japanese, they must have many mirror sites as Japan governmental authorities can work, find and restrict the main and mirror sites of Betpanda if they know.
This must be the most possible reason why betpanda create a new link (mirror) for Japanese gamblers, maybe betpanda see that there are many potential gamblers from Japan while if gambling is banned in Japan means that most Japanese gamblers are unable to access gambling sites.
It is basically similar to what is done by Stake and Bitsler with their US version which is to serve US gamblers, of course it is just speculation but I think there is no other reason why betpanda need to create specific link to Japan.