Kuroinu

From the introduction: Our story takes place in the the continent of Ostia/Serenus. For many years the monstrous races of the Northland, called Legion, have raided the south raping the women, and pillaging the countryside until the south managed to repel them. However a few hundred years ago this cycle changed with the appearance of the Black Citadel. The Dark Elf queen Olga Discordia, an incredibly powerful witch, bolstered Legion with her magic powers making them unstoppable. However the High Elf Celestine, considered to be a goddess, saw visions of Legion’s rampage and united the Southern Kingdoms into the Seven Shields Alliance, stationing themselves in seven legendary fortresses to beat back the Legion, and so the war has gone on for hundreds of years.