The Netherworld is a place where only demons, which are creatures of the shadowy depths, reside. It was always going to be tough for Salvos to survive in this horrific environment because he was a curious newborn Demon who liked to make friends. And when a mysterious Demon King threatens the life of her companion, she will need to evolve, adapt, and earn experience in order to do what is necessary to save him. Even if it means leaving him behind and being thrust into a strange world with monsters, Humans, and a clear blue sky where she is mocked for being a Demon born. Since the rule of evolution dictates that the fittest individuals live, Salvos will prevail.