Fate: Song of Grail

Two individuals who lost everything in the Great Fire at the end of the 4th Holy Grail War, one whose past was taken away, the other who lost their purpose. Both have found peace as they lived together as family. However, in the wake of the 5th Holy Grail war, they must face several opposing forces in order end the Grail War once and for all. [Spoilers for Fate Stay Night and Zero]