The teases are over! Gust's new PlayStation Vita game has been revealed in this week's Dengeki PlayStation to be (deep breath!) Sarge Concerto -- Sherno Sarge: Ushinawareta Hoshi e Sasagu Shi.
Only a few details have surfaced so far from the magazine, which doesn't hit retail shelves until later this week. The game is said to be an online title (possibly exclusively online), and its genre is listed as ETC. The main character (although possibly not the character you control) is a girl named Ion. She was shown in the teaser ads Gust shared late last year.
Gust appears to to have big plans for Sarge Concerto as a franchise. The Vita game is the first entry in the franchise, which will be developed on a variety of platforms. The various entries will take place in the same world but in either different time periods or worlds of different possibilities (I think this may mean a parallel version of the same world).
Although we're just now hearing about it for the first time, the Vita title is due for release on April 26.