Social and mobile giant DeNA is being investigated by Japan's Fair Trade Commission over anti-competitive practices.
According to the Japan Times DeNA has tried to stop developers from providing games and content to rival company Gree, and also blocked users of its Mobage-town network from accessing content developed for titles on Gree's alternative service.
The FTC is alleging these unfair practices have violated anti-monopoly laws in the region.
DeNA intends to launch a version of Mobage-town in the US and Europe with recent acquisition Ngmoco, with a roll-out expected next year. Mobage-town has over 20 million users in Japan.