On this world, humans are invaded by the existence called Yuugenshu. People were able to survive because of the floating continent, Obie Crea, protected by Priestesses’ prayers. Sheltis had once aimed to become a Sen’nenshi—a partner of Yumii, his childhood friend and also a Priestess. However, because he fell from the continent to the Eden , he harbored Mateki, what only Yuugenshu have, inside his body, and was exiled from Sophia where Yumii lives. Meanwhile, Yumii was hoping for Sheltis to become her Sen’nenshi, but because he fell, her wish is still unfulfilled. A multi-layered world fantasy where their feelings intertwine!

Three quarters of the world is the world of the dead. The world has been invaded by phantoms. One day, a boy named Nagi finds in the mountains of scrap wood a mechanical teenage maid girl. He immediately takes her home to repair her. The first things that Elise, this mysterious mechanical maid, says is, “Good morning, Nagi.” Who is this mysterious silver haired girl? The fate of the world rests in their hands.