The start of this series should explain the function of the world they're in and what's going on. All I'm getting about this TV Series is a lesbian vibe and awkward moments, but I'm sure that this can be a great show with a little more detailing and adventure.
"Originally titled Rage of Bahamut: Manaria Friends, the series is an adaptation of the "Mysteria Academy" or "Manaria Mahō Gakuin" event in the Rage of Bahamut social game, and is unrelated to the second season of Rage of Bahamut: Genesis, which was also adapted from the game." - wikipedia
the show is part of a universe, and the specifics we will get to know overtime w/ gradual world building