The story is set in 2015 when magic still held a strong influence over the world. To oversee the two worlds that operated on science and magic, a human survival and security group called Chaldea was established to prevent humanity's ultimate demise. Thanks to tireless researchers, human history was ensured to continue for another century until Chaldea's future realm unexpectedly vanished. In 2017, the destruction of humankind was no longer a theoretical possibility but a proven fact. The cause of this annihilation had occurred in 2004 in the Japanese city of Fuyuki. An "unobservable realm" had suddenly appeared in the city that had never existed before. To investigate and potentially eliminate the singularity behind humanity's crisis, Chaldea launched the "Holy Grail Expedition" under the Grand Order. (Source: Adapted from ANN)