The Humane Continuity Guarantee Agency, Chaldea, observes a world that can not be seen only with magic. One day, the near future observation lens Shiva will incinerate the future of humanity in 2017-it has been proven that humanity will be extinct. "Unobservable areas" suddenly appearing in various places in history-singularities. Chaldea assumes this is the cause of human extinction and decides to travel in time to the past. Members of Chaldea, such as Tatsuka Fujimaru, Mash Kyrielight, Leonardo da Vinci, Romani Archiman, intervene in singularity events, A forbidden ritual to elucidate or destroy this-the name is being searched for “the Holy Grail (Grand Order)”. The wise king Gilgamesh dismantled Babylon and rebuilt it as a fortress city, Babylonia, to stop the onslaught of evil beasts. Gods, beasts, and humans. The battle for the survival of the species has now begun..