Yuuki Yuuna wa Yuusha Bu Shozoku  

結城友奈は勇者部所属, Yuuki Yuuna is a Hero Club Member, Washio Sumi wa Yuusha de Aru, Yuuki Yuuna wa Yuusha-bu Shozoku, Yuuki Yuuna wa Yuusha-bu Shozoku 3, Yuuki Yuuna is a Hero Club Member 3, 結城友奈は勇者部所属 3

The story takes place in the era of the gods, year 300. Yuuna Yuuki lives an ordinary life as a second year middle school student, but shes also a member of the "Hero Club," where club activities involve dealing with a mysterious being called "Vertex."(Source: ANN)