Due to an amendment in December 2018 of the Unfair Competition Prevention Act in Japan, certain gaming-related activities and services have now been declared illegal. This includes:
Distribution of tools and programs for modifying game saves
Selling product keys and serials online without the software maker's permission
Game save and console modding services
As such, sales of products such as Pro Action Replay and Cybergadget's "Save editor" have been discontinued.
It's meant to ban sale of hardware devices and services that allow playing pirated games on Switch and such, but due to the way it's worded it just bans them all.
We really need to push for more right to repair laws and things not produced by the copyright holder (say for 5 years) should lose all copyright protections.