Gree Inc., Japan's second-largest social-network game operator, agreed to buy Funzio Inc. for $210 million in cash in its biggest acquisition to add games for mobile phones, including "Crime City."

The transaction is expected to close this month, Tokyo-based Gree said in a statement Wednesday. The company will fund the purchase of Funzio, a San Francisco-based mobile game developer, through bank loans, it said.

The Japanese company, founded by billionaire Yoshikazu Tanaka, is trying to spur overseas sales as its growth at home may slow with the imposition of self-regulation, such as limiting downloads of virtual items by minors. Gaining Funzio will give Gree access to titles including "Kingdom Age" and more software developers to speed up introduction of new games.

Gree had more than 190 million users as of December, according to the statement. There have been more than 20 million downloads of Funzio's games through social networks including Facebook Inc. and Google Inc., according to Gree.

The purchase is Gree's biggest acquisition since its listing in 2008, according to data compiled by Bloomberg.