Image: Pocketpair
Sony has already launched the PlayStation 5 port of Palworld in 68 countries and regions worldwide. Japan isn't one of those countries, though. According to machine translation, the official Japanese account for the game said on X that the Japanese release "has not yet been decided." They didn't elaborate on the reason.
However, the most likely reason is the patent infringement lawsuit Nintendo and The Pokémon Company filed against Palworld developer Pocketpair last week. The most recent statement from Pocketpair came out on the 19th, acknowledging the lawsuit. But the company claims it is unaware of the patents it infringed, and its rep said they haven't been notified about the details yet.