Nintendo has filed a lawsuit against five companies in Japan which imported equipment that enables illegal game programs to be played on the Nintendo DS, such as the R4 cartridge.
The company is aiming to put a stop to the marketing, sale and importing of the Chinese-made hardware and software.
Other firms backing the lawsuit include Capcom, SNK, Taito, Tecmo and Square Enix.
You can get hold of these devices easily from internet retailers such as Amazon and on auction sites like eBay. They allow gamers to download hacked files to a memory card and then slot it into the DS by using a specially made cartrigdge.
Nintendo said in a statement that such piracy "is causing severe damage to our company and software makers, and this is something that we cannot possibly overlook."