At Chaldea Security Organization, the final Master of humanity Ritsuka Fujimaru and his Servant Mash Kyrielight have journeyed through six regions of differing eras in order to retrieve their future lost due to the "incineration of humanity" caused by the Mage King. And now, to repair the final Singularity, the pair head forth into ancient Mesopotamia. As soon as they land in those lands where the gods exist on an everyday basis, they are assaulted by an overwhelming number of Demonic Beasts. And just as suddenly, a beautiful girl descends down from the sky.

Fujimaru's entourage successfully has an audience with the wise king Gilgamesh ruling over Uruk. Fujimaru suggests to Gilgamesh that he wants to receive the Holy Grail that is causing this Singularity in return for defeating the Three Goddess Alliance that is putting all of Mesopotamia into a panic. However, Gilgamesh declares that he will not need the assistance of Chaldea for Uruk to face its perils. The situation turns extremely delicate, but then, Ishtar, the patron deity of Uruk, suddenly intrudes upon them, and they all end up in battle.