Does it even let you into the site to navigate around? Or does it just block the radio streaming?
I tried the site and it worked fine from Australia, but I couldn't read the language to find the radio part.
It blocks the radio streaming service. It will let you navigate around the website itself.
On the top left corner you should be able to see the website logo and underneath which country you are trying to access from. The objective is to make this corner display "Japan" instead of any other country.
In addition if the website displays
In bold text near the top centre, that means you cannot use the radio service as it literally translates that you cannot listen to the radio because you are out of the service region.