Zynga confirmed tonight that it has accelerated its plans to enter Japan by buying a local social game developer called Unoh. Nikkei reported yesterday that the price was around $11.6 million (subscription required), although Zynga isn’t saying more.

Unoh is almost a decade old, with a few hit games of its own, though nothing at the scale Zynga enjoys in the United States. One of its games, a city builder called Machitsuku, has three million users on the mobile social platform Mixi, according to TechCrunch.

The Mixi connection helps explain how Zynga may have come to acquire Unoh. Mixi enjoys a close relationship with the tech giant and mobile operator Softbank, which just invested $147 million in Zynga.

Although Zynga hasn’t a great deal publicly about its plans for Japan, it’s clear that the company is moving quickly. The company’s release tonight quotes CEO Mark Pincus calling Unoh “a perfect complement to the top-notch team we have already begun to assemble in Japan,” and refers to both localizing existing Zynga games and building new games for the market.