The Sanshu Middle School Hero Club is granted magical-girl powers by the deity that protects their world.
Length: 12 episodes
I love me some magical girls and dark anime. Yuki Yuna is a Hero combines the two.
The girls belong to the Sanshu Middle School Hero Club, volunteering in the community and helping other clubs out. They soon discover that the true purpose of the club was to gather girls who showed a high “hero aptitude” in preparation for the day when they would be called upon to defend their world.
The series starts out fairly light and innocent and then gets darker about halfway through as the girls discover more about the Hero System that grants them their powers and find out the true nature of the world they live in.