Farmville developer Zynga has teamed up with telecommunications/media corporation Softbank to create Zynga Japan, a joint venture focusing on social games and the local mobile market.

Along with announcing the Tokyo-based joint venture, Softbank revealed that it's completed a previously reported $150 million investment in Zynga, boosting the San Francisco's total amount of venture backing raised since its founding three years ago up to almost $370 million.

With the establishing of Zynga Japan, the developer is taking its first step into Japan's growing internet and mobile businesses. The joint venture looks to tap into Japan's history of gaming while leveraging Softbank's mobile and web technology to produce what the two firms hope will be "the best social games in the market".

"We're excited to partner with Softbank to bring Zynga's social games to Japan and gain insights from the Japanese market," says Zynga founder and CEO Mark Pincus. "As one of the most innovative technology companies in the world, Softbank is bringing the mobile internet to consumers making the social web more accessible to people everywhere."