My ASO is First-Rate

It has been over a thousand years since humanity first crossed over to the world of Alkoresh, helped to restore the fractured Grand Alliance of free peoples and together defeated the cruel tyranny of the Demon King and his minions. The years that followed would have their troubles, but by and large peace prevailed. However, the thousand-year cycle is turning once more and the Demon Realm threatens to invade anew. Meanwhile, in a small nation at the crossroads of the peoples and powers of the world, an unassuming Army staff officer takes up his new post, unaware that he and his talented assistant are standing in the vortex of events that will shape the fate of the planet and every living thing in it.