As the Fifth Holy Grail War looms in Fuyuki City, high school student Rin Toosaka prepares to showcase her lifelong magical training by participating as a Master with her summoned Servant, Archer. Unexpectedly, Rin's acquaintance Shirou Emiya is also entangled in the deadly conflict, prompting Rin to propose a temporary alliance. Amidst their budding bond, Rin delves into Shirou's beliefs and destiny while keeping her eyes fixed on the ultimate prize—the Holy Grail, a mystical artifact that grants the victor any wish their heart desires.