Zynga, which developed popular games for Facebook, such as 'Farmville,' said the mobile products effort in Japan will be a joint venture between Zynga Japan and SoftBank, which has a Japanese mobile phone subsidiary.

The companies did not say how much Zynga paid for Unoh.

Unoh, of Tokyo, was founded in 2001 and created popular Japanese games, Machitsuku!, Band Yarouyo! and Kaizoku Chronicle.

Zynga Japan plans to work with Unoh to tweak its own social games for the Japanese market, Zynga said in a statement. Unoh will also be central to its efforts to develop new games for people in Japan.