Just blacklist Japanese IP addresses. It is incredibly doubtful that Japanese publishers would care about overseas "lost" sales of the products they often dont even offer for sale outside of Japan anyway. At that point, rename it to something different and continue as before.

Sucks for the people in Japan, but thats just how companies ruin useful tools because of profits.

The website backup is still available on Internet Archive (http://web.archive.org/web/20230705071353/https://itazuraneko.neocities.org/).

Some links may be broken though.