They shouldnt be able to sue for that cause a patent only lasts for 20 years in Japan. I saw some guesses that there might be a patent for one of their legends games that they are suing for.

Its hard to sue shin megami tensei when megami tensei came out first. Also Nintendo is apparently sueing for patent infringment and im curious which patent they are suing for cause most of the og patents should be expired by now. The best guess I’ve seen is maybe patent related to either legends game.