The devices which enable the playback of pirated and homebrew software on the Nintendo DS are now both illegal to import and to sell in Japan.
The R4 is a flashcard device, but similar devices utilize SD cards to load game ROMs and other media onto the Nintendo DS and DSi.
While Nintendo succeeded in making the devices illegal to sell in Japan in 2009, they could still be imported, a natural option for shopping in the island nation.
The devices' stunning popularity has been curbed in recent years as Nintendo has had Amazon and eBay prohibit sale of the devices, while pursuing legal action against smaller sellers the world over.
As with other piracy and counterfeit concerns, Nintendo's agenda extends to all territories where its products are sold.