Miitomo the Social Media mobile app developed by Nintendo got a release date today announced by the official Nintendo Japan Twitter.
With Nintendo’s continued push towards the smartphone app market, enter Miitomo described by Nintendo as ‘a free-to-start communication application that helps friends share fun personal facts and interests…‘.
— 任天堂株式会社 (@Nintendo) March 11, 2016
Even though this was announced on the Japanese Nintendo account it is pretty safe to assume that 17th March will be the release date across the countries where Miitomo is open for registration. Please be aware that you will have to Pre-register before the 17th when the service goes live.