The Holy Grail War is a battle royale among seven magi who serve as Masters. Masters, through the use of the command seals they are given when they enter the war, command Heroic Spirits known as Servants to fight for them in battle. In the Fifth Holy Grail War, Rin Toosaka is among the magi entering the competition. With her Servant, Archer, she hopes to obtain the ultimate prize—the Holy Grail, a magical artifact capable of granting its wielder any wish. One of Rin's classmates, Emiya Shirou, accidentally enters the competition and ends up commanding a Servant of his own known as Saber. As they find themselves facing mutual enemies, Rin and Shirou decide to form a temporary alliance as they challenge their opponents in the Holy Grail War. [Written by MAL Rewrite]

The Fifth Holy Grail War in Fuyuki City has reached a turning point in which the lives of all participants are threatened as the hidden enemy finally reveals itself. As Shirou Emiya, Rin Toosaka, and Illyasviel von Einzbern discover the true, corruptive nature of the shadow that has been rampaging throughout the city, they realize just how dire the situation is. In order to protect their beloved ones, the group must hold their own against the seemingly insurmountable enemy force—even if some of those foes were once their allies, or perhaps, something more intimate. As the final act of this chaotic war commences, the ideals Shirou believes will soon be challenged by an excruciating dilemma: is it really possible to save a world where everything seems to have gone wrong? [Written by MAL Rewrite]

After a mysterious inferno kills his family, Shirou is saved and adopted by Kiritsugu Emiya, who teaches him the ways of magic and justice. One night, years after Kiritsugu's death, Shirou is cleaning at school, when he finds himself caught in the middle of a deadly encounter between two superhumans known as Servants. During his attempt to escape, the boy is caught by one of the Servants and receives a life-threatening injury. Miraculously, he survives, but the same Servant returns to finish what he started. In desperation, Shirou summons a Servant of his own, a knight named Saber. The two must now participate in the Fifth Holy Grail War, a battle royale of seven Servants and the mages who summoned them, with the grand prize being none other than the omnipotent Holy Grail itself. Fate/stay night follows Shirou as he struggles to find the fine line between a hero and a killer, his ideals clashing with the harsh reality around him. Will the boy become a hero like his foster father, or die trying? [Written by MAL Rewrite]

As the Fifth Holy Grail War reaches its conclusion, Saber repeats her final duty from the previous war in order to end the vicious cycle once and for all. With the decisive blow draining her remaining mana reserves, Saber's body begins to dissipate. She utters a tearful farewell—but Rin Toosaka reaches out to her at the last moment. The future has been changed, and a new beginning awaits. [Written by MAL Rewrite]