The story revolves around Shirou Emiya, a hardworking and honest teenager who unwillingly enters the fifth iteration of a to-the-death battle royale called the Holy Grail War, where combatants fight with magic and Heroes throughout history for a chance to have their wishes granted. Orphaned and the sole survivor of a massive fire in Fuyuki City as a child, Shirou was taken in by a retired magus named Kiritsugu Emiya, who died some years later. Shirou's feelings of responsibility for those who died and his own salvation through his father formed a strong desire for justice and peace in him. Thus, he earnestly trains his body and minuscule ability with magic with the goal of helping others, even if people often abuse his generosity. One evening, Shirou unexpectedly comes across two warriors, Archer and Lancer, fighting at his school. He is attacked and nearly killed by Lancer, but Archer's master, Rin Tohsaka, manages to revive him just before death. However, Lancer attacks again, and just before Shirou is about to be killed, he accidentally summons his Servant, Saber, who saves his life. With this summoning, the marks of the Command Seal appear on Shirou's hand, formalizing his entry as a Master into the Holy Grail War. As Saber forces Lancer to flee, she engages in combat with Archer, but Shirou accidentally stops her with his magic upon seeing Rin, his schoolmate. Shirou and Rin decide to form an alliance to fight against other mages. Through the priest Kirei Kotomine, Shirou learns about the Holy Grail War's context. Although initially hesitant, he decides to participate to avoid future catastrophes happening as a result of wishes granted by the Holy Grail. As the war continues, Shirou starts developing his own skills as a magus by imitating Archer's abilities, and Rin notes striking similarities between the two. However, in a battle against the servant Caster in an attempt to rescue his guardian Fujimura, Shirou loses control of Saber, who is imprisoned by Caster. Shirou vows to fight with his own magical strength to stop the war and save his friends. Archer betrays Rin during a fight against Caster, but Rin reforms her alliance with Shirou. With Lancer's help, the duo manages to free Saber from Caster, who is then killed. To gain more allies, Rin and Shirou decide to team up with Illyasviel von Einzbern and her servant Berserker. However, Gilgamesh, Kotomine's former servant, arrives and kills both Illya and Berserker before Rin and Shirou can stop him. At Illya's villa, Archer challenges Shirou to a fight, hoping to destroy Shirou's goals of being a hero. Confused, Saber demands to know what his true intentions are, and Archer reveals himself to be a version of Shirou from the future, who became a heroic spirit after becoming disillusioned with the path he took. However, Shirou accepts his future regardless of Archer's regrets, deciding to stick to Kiritsugu's ideals of being a hero. Gilgamesh tries to kill Archer and Shirou, but the former sacrifices himself to protect the latter. Gilgamesh takes Illya's heart, planning to use his other master, Shinji Matou in order to summon the corrupted Holy Grail. In order to follow Archer's hopes, Rin passes Shirou her mana to fight Gilgamesh to replicate Archer's powers. As Shirou nearly kills Gilgamesh, Archer uses the last of his strength to deliver the final attack at their enemy while assisting Saber to destroy the Holy Grail. With the war concluded and the servants gone, Shirou and Rin move to London to learn more about magic, and Shirou vows once again to retain Kiritsugu's ideals. In a post-credits scene, Archer appears in another dimension, and disappears as he remembers his past self's words, just as another, younger, hooded person appears in the same field, Dou watch and enjoy.
