Driven to the verge of extinction by "Aragami," a race of all-devouring monsters, humanity makes its last stand in isolated points of resistance. Invulnerable to conventional damage, only "Oracle Cell" weapons—composed of the same matter which makes up Aragami—can kill these creatures. However, due to their god-like ability to adapt, the Aragami soon develop further immunity. Having no other hope of fending off the enemy, the remnants of human governments decide to detonate a nuclear reactor and wipe out the monsters facing Eurasia. The soldiers tasked with this mission are aided by three "God Eaters" dispatched from the Fenrir Far East Branch, an organization controlling what remains of Japan. The state-of-the-art weapons they wield, called God Arcs, are supposedly capable of piercing through Aragami skin and tearing their cores out, pulverizing the monsters. These mighty warriors may just be humanity's last hope of fending off the Aragami threat and averting total extinction. [Written by MAL Rewrite]

In Fuyuki City, a long-lived ritual involving battles between seven magi and their servants is taking place. This ritual is known as the Holy Grail War and it promises to grant the victor any wish. With the war now entering its fifth iteration, the stage is set for Rin Toosaka to succeed her father's legacy. Rin wishes to summon Saber, said to be the most powerful class. But when she miscalculates and summons Archer instead, how will she fare in the battles that lie ahead of her? [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]

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]