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, Shirou Emiya, 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.

Fate/Stay Night: Unlimited Blade Works is based on the second route of Type-Moon's Fate/stay Night visual novel. It was originally released in 2004 for Microsoft Windows and later ported to the PS2 and PS Vita in the form of an updated edition, with bonus content, titled Fate/stay Night: Réalta Nua. The visual novel received a port to Steam and the Nintendo Switch in 2024 titled Fate/stay Night REMASTERED which included its first official translations to English and Simplified Chinese as well as updated graphics.