Read manga: So-Ra-No-Wo-To

manga
Summary:

The story takes place in an imaginary town Seize (the model cities are Cuenca and Alarcón Fortress in Spain). A long war brings a gradual decline to the world. People disappear from the town and fishes cease to exist in the sea. In this quiet world, five girls guard a fortress and play brass vividly. [Source: MAL News]