DeNA is a company familiar to those that follow Nintendo closely, courtesy of the corporate partnership between the companies and DeNA's role in handling back-end services and networks for the big N. Primarily brought in for its expertise in mobile and networks, DeNA's imprint can be found in Miitomo and - very likely - the Nintendo Account system.
It's a potentially valuable relationship for both companies, and it seems that DeNA is shifting its focus to that partnership and backing away from broader ambitions in the mobile market. Having been a major player in the mobile space in the past, the company has now confirmed that it's closing down its US-based subsidiary, DeNA Global.
In the Game Business, DeNA has focused on three key regions — Japan, China, and the West. During the fiscal year ended March 31, 2016, DeNA optimized the organizational structure and game portfolio in the West and has been developing games for the Western market with a lean structure since; however, since the games did not meet expectations, DeNA has decided to dissolve and liquidate its West subsidiaries, including DeNA Global, Inc.
In addition to struggles making an impact in the current market as a major mobile publisher, recent remarks by analyst Dr. Serkan Toto have also suggested that the company's responsibilities and roles with titles like Super Mario Run are more significant than previously expected. Though Nintendo is still leading the core design and oversight of the iOS project, DeNA is reportedly active in the technical aspects of the game's development.
Ultimately this seems like a move designed to enable DeNA to prioritise its business; with the wide-held belief that Nintendo can achieve significant success in mobile, that's certainly understandable.