In the land of Amestris; conspiracy, corruption, and a war in secret stirs within the vicinity of Alchemists and Magi. A Ruler-class Servant comes as the mediator of the war for the Holy Grail, and her meeting with the Fullmetal Alchemist defines the fates that theirs, and others, have intertwined.

After the blast of Excalibur took Saber away in the Fourth Holy Grail War, she is transported to an unfamiliar world. Now, as Arturia Pendragon, the Knight who was once known as the One and True King, will lead again as Inquisitor and bring order to the world. But will she bare the role to lead again? Will her followers help her heal, as they see her their only hope for this world?