Another day, another DeNA departure.

Jason Oberfest, who was vice president of social applications for the mobile-gaming platform, has left to co-found a mobile health startup called Mango Health. Oberfest joined Ngmoco in September of 2009, just months before it was acquired by Japanese gaming giant DeNA in a deal worth up to $403 million. Now that the first date has just passed for the $100 million earnout, it looks like we might see more movement from employees of the U.S. subsidiary.

Ngmoco was acquired as a key part of DeNA’s foreign expansion plans. Flush with cash from the Japanese market, both DeNA and its rival GREE are looking to build out global mobile-gaming platforms that replicate their virtual currency-dependent model in Western markets. Ngmoco launched DeNA’s Mobage gaming platform formally last fall and has signed up prominent developers including Nimblebit, TinyCo and Glu Mobile.

Oberfest has not replied to requests for comment on what Mango Health is or what his next plans are. He’s entering a hot space: Massive Health raised $2.25 million from Andreessen Horowitz, Charles River Ventures and others. Venture firms like Accel Partners and NEA are also contributing to a health startup incubator called Rock Health.

We’re also seeing departures from some of the other U.S. assets DeNA acquired the same year. Two co-founders from Gameview Studios, another startup DeNA acquired around the same time it did the Ngmoco deal, have also recently left the company. Gameview is behind Tap Fish, a virtual aquarium game that consistently ranks as one of the top-grossing Android apps. The third co-founder, Irfan Virk, stayed on to start a Canadian gaming studio in Vancouver for DeNA.