If reports are to be believed, Japanese gaming giant DeNA is considering an acquisition of iPhone publisher Ngmoco for over $400 million. Rumors have it that the price is above $400 million, although that likely includes a large earn out, or a payment based on whether Ngmoco hits performance targets.

Former EA exec Neil Young founded Ngmoco in 2008 as a developer of iOS games. Some of their top games are Rolando, Word Fu, Flick Sports Fishing and We Rule. In August, Ngmoco received funding from Google Ventures. DeNA acquired Gameview, another mobile social-game development company, in September.

DeNA is predicting to generate more than a billion dollars in revenue this year in the Japanese mobile games market, where mobile gaming is much more advanced. Ngmoco has promised that the U.S. could potentially be a much bigger market than Japan’s.

DeNA is head

ed by Tomoko Namba. The company is in straight rivalry with Zynga to rule the social games market. While DeNA comes at the market from the mobile side, Zynga is aggressive in Facebook gaming.