The existence of console modding services have always been in a bit of a legal grey area. While it is generally accepted that provided the modifications are not used for piracy and are solely for personal use, things become a bit trickier when the developer of such a mod decides to distribute or sell it. Except in rare circumstances, however, such as the recent arrest of a man from Ibaraki Prefecture in Japan named Tomoyuki Miyamoto who sold Super Famicom Mini consoles with extra games they had hacked into the system, it is rare that any action will be taken due to the legal ambiguity. Even in this circumstance, the act of modification is not what they were arrested for, but for the breach of copyright for the newly-added games to these modified systems.
This could be changing in Japan soon, due to recent changes to Japan’s Unfair Competition Prevention Act. While the act of modifying one’s personal console hasn’t been made illegal through this amendment, it will now be illegal to offer a service that modifies or hacks a games console. These changes expand beyond this however, also criminalising services that offer the editing/hacking of save data, the distribution, sale or auction of a serial code or product key for a game without the software maker’s permission alongside the distribution of save data editors and programs. Being found guilty of these acts could see you fined up to 5 million yen or imprisoned for up to 5 years if charged criminally, with civil action to claim for damages also possible.
While it is perhaps understandable to want to protect manufacturers and software developers from the damages that could come from hacks and modifications, there is the argument that this law goes beyond what would be reasonable to prevent such damages. Some popular products like Cybergadget’s save editors have been discontinued in response to the new law while some popular modding tools like SplatHeX, a tool that allows users to modify their Splatoon save data, have also warned Japanese fans that using their tools will now be illegal.
In any case, people in Japan who want to modify their games or save data will want to be very careful that their actions won’t fall foul of the law going forwards.