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?