R4 cartridges, which are a blanket term for all flash carts (or Majicon) for the DS, DSi, and 3DS, have been the bane of Nintendo's existence for many years now. Said devices allow one to load countless games into a single physical housing, which are often acquired through illegal means.
In recent years, Nintendo has worked closely with the Japanese government to have the sale of such devices made illegal, which is currently the came. Though they may have scored their biggest victory yet; according to Kotaku, the Japanese Ministry of Economy, Trade and Industry, has announced that the importing of any R4-like carts is strictly prohibited by law.
As noted, it's already against the law to sell Majicons in Japan; earlier this year, one retailer in Saitama was arrested and jailed for distributing R4s via the internet, the first of its kind.
R4 cartridges used to be commonplace in both brick and mortar stores and online retailers within Japan, but due to the crackdowns, purchasing them directly from their place of origin, China, has been the only real option left.
This new ruling is no doubt a massive blow for those who both pirate software and dabble in the homebrew scenes in Japan. Though it remains to be seen how truly effective it will be.
