Over three-hundred years ago, the necromancer, Emperor Keir, almost took over the entire continent of Erebu. It took a coalition of nations from all over the world to defeat him and his army of mindless undead and loyal living subjects. But that was not the end of him, he created a 'Heart' to safely hold his soul, which would allow him to return to life later.
In the present day, an army of demons have slaughtered their way across the continent. Most of the human inhabitants are dead, a few million survive in strongholds waiting for a miracle, and the rest of the world has abandoned the continent. In desperation the Eldritch Council, which was formed to prevent the spread of necromancy and ensure Keir would never be released, has resurrected the one time Emperor.
Now Keir has to use his powers to save the continent from an endless tide of demons, while dealing with allies who don't trust him, and under the effect of several geas that limit his actions and plans.
At least these problems put being resurrected as a woman into perspective.