The small device fits into the DS's cartridge slot and allows games stored on a Micro SD card to be played on the DS. It can be used to play both homebrew games developed by individual programmers and hacked games and, not surprisingly, it's the latter that upset Nintendo.

In July last year, Nintendo and 53 game software companies filed a lawsuit against five companies they alleged sold and imported the R4. Retailers in Akihabara quickly moved to pull the R4 from sale for fear of getting sued themselves, although those fears are apparently waning.

This week, several retailers on the main Chuo Dori street that runs through the center of Akihabara are openly advertising the R4 for sale with posters that invite potential customers to come inside the shop to buy the device.

Just last week, Yahoo Auctions, the most popular online auction site in Japan, warned users that based on the outcome of the lawsuit filed by Nintendo and its partners they could face legal action in the future.

The suit, which was filed at the Tokyo District Court, is currently underway and is expected to end in the coming months at which time a ruling is expected, Nintendo said.