The Fifth Holy Grail War is set to begin in Fuyuki City, and Rin Toosaka, a high school student who has dedicated her life to becoming a powerful magus and Master in the war, is ready for the bloodshed and despair that awaits. With her Servant, Archer, by her side, Rin enters the fray. Unexpectedly, Rin discovers that her acquaintance, Shirou Emiya, is also a participant in the war. With an eye on the prize - the Holy Grail, a relic that grants the wishes of the victorious - Rin proposes an alliance with Shirou for the time being. As their partnership deepens, Rin grows more familiar with Shirou's beliefs and destiny. Despite this, her determination to emerge triumphant remains unshakable.