Hmm... Nifty was (is?) a value-added network inside of Japan. These links request for your Nifty access id, which seems to mean that your Nifty account will be charged.
There is no way that I am aware of, to obtain a Nifty account if you aren't in Japan, so you would need to ask for a Japanese person's assistance.
However...
Provision #3 of the agreement states that supplying it to a 3rd party is contrary to the contract.
It would appear that this software is very traceable, and although you likely want to pay the money and obtain a legal copy, this is not really possible (at least, via the Nifty download here) unless you move to Japan. It is also possible that it could be available for sale in Japanese stores as a boxed product. Again, the assistance of a friend who is a Japanese resident would be helpful in this case.