Mobile social network OpenFeint, which now belongs Japan’s GREE, is switching CEOs today as co-founder Jason Citron steps down to “pursue other interests.” GREE International’s Naoki Aoyagi moves into the position.

Aoyagi (pictured) joined GREE back in 2006 as CFO and has a cumulative 10 years experience in various tech, media and financial industries, including a four-year stint at Deutsche Bank. According to his LinkedIn profile, he became CEO of GREE Intl., an international division, nine months ago, well before the OpenFeint acquisition. It is not immediately clear if Aoyagi will remain CEO at GREE Intl. while serving as CEO of OpenFeint.

UPDATE: A publicist for OpenFeint tells us Aoyagi will not remain CEO of GREE Intl.

UPDATE 2: The same publicist says that he was given the wrong information and that Aoyagi will remain CEO of GREE International.

Not many details are available yet as to where Citron is headed or what actions Aoyagi will take in his new role, but a terse press release announcing the move says that in the coming weeks, we can expect an announcement around integration plans between the U.S. operations of both companies. Citron entered the tech industry via the video game industry, starting off as a game programmer and then becoming an entrepreneur through incubator YouWeb’s support. He sold OpenFeint to GREE for $104 million.

Currently, OpenFeint claims a network of 120 million registered users and 7,000 games available through its service. Last we heard, the company was launching a single sign-on service for its customers.