The Eternal War

It's the year 3168 Amane Shinra keeps having strange dreams of a person forging a contract with him. Each time he falls asleep that dream plagues his mind. He keeps asking himself if he should be scared or happy. You see in this world a select amount of people from each sector get sent to a different planet to fight to the death. As a sacrifice to the dead. It's rumored when you die in this war you don't just die, you get turned into an undead and is forced to do work for the fifteen overlords of hell. No one knows what the work is or if it's even true but everyone who was killed during the war has returned the same age they were when they entered. With no memories of their work in the underworld.