In the Holy Grail War, seven magi chosen by the Holy Grail itself must summon seven Heroic Spirits to compete for the omnipotent Grail, a magical device that grants the victor any wish they desire. After three inconclusive wars, the fuse has now been lit once again for the fourth time.

In the midst of an industrial revolution, the people of Hinomoto fight hordes of undead creatures, known as Kabane, using powerful armored trains.