World:The Sixth Holy Grail War
The Fifth Holy Grail War ended in an impasse. The Holy Grail was tainted with the darkness of Angra Mainyu, but the crisis was averted when the alliance of Emya Shirou, Toshaka Rin and the Servant Rider manage to surpass all obstacles and defeat the darkness within the Grail. Rider takes Sakura and Rin away, while Shirou remains behind to destroy the Holy Grail for once and for all - and is saved by Ilyasviel. Barely surviving, Shirou returns home to live with Sakura and Rider, while Rin goes off to the Magic Association - but a surprise comes to them.
The Holy Grail was not destroyed, after all - its transcendental entity continued to exist, even while its physical, corrupted body was destroyed. After the neutralization of Sakura, Shirou was the last remaining Master with a Servant (Rider, after their alliance contract), and therefore the Holy Grail determined him the winner of the Fifth Grail War.
Shirou's desire was to undo all the evil that had been caused during the Fifth Grail War: a pure, powerful wish that was granted by the Holy Grail. All those who had been killed during the War were restored to life, as all damage done was restored, and the memories of thousands of people were restructured by the Holy Grail. The Servants Saber and Archer were brought back to life, lifted from their Heroic Spirit statuses, and managed to stay in the world the same way as Rider had. Darkness rolled away and turned into memory, and the sky above Fuyuki City grew bright and warm.
Until, ten years later, the Holy Grail would surface again and call for the Sixth Holy Grail War...