The importing of the infamous R4 cart - or similar flash cart devices for DS - has been outlawed in Japan.
The R4 cart and those like it are read-writable cartridges for the DS which allow users to download and play pirate games.Nintendo has been locked in legal battles globally over the distribution and sale of such devices, as it made efforts to curb rampant piracy on its first dual-screen handheld.
The Japanese Ministry of Economy, Trade and Industry (translations via Kotaku) has announced it is now illegal to import such devices into Japan, where their sale has already been banned.
Game copying devices like the R4 were ruled illegal in France late last year, bringing the country in line with other European territories including the Netherlands, UK, Germany, Italy and Belgium, Nintendo said at the time.

http://www.computerandvideogames.com...awed-in-japan/