10 years after the 5th Holy Grail War took place, a 6th one has began when Rin was was prevented from dismantling it. Now Tamiko Katou finds herself trapped in the battle with her servant Caster by her side and ends up confronted by the mysterious Archer Emiya who has been summoned to prevent humanitys extinction. Alternate Timeline, follows the UBW route of Fate/stay night.