Mahou Shoujo Ikusei Keikaku

The hit smartphone game Magical Girl Raising Project is not only free, but one in tens of thousands of players will win real-life powers. In N City, sixteen of these lucky girls help the city's citizens—until upper management announces that each week, the least productive magical girl will lose her gifts. But this is no ordinary contest, and as the rules become increasingly sadistic, the competition to keep their powers becomes a vicious battle for the girls' very lives... (Source: Yen Press)