In the ongoing War of the Holy Grail, seven magi summon Heroic Spirits to vie for the miraculous power of the 'Holy Grail.' Amidst the fourth iteration of this intense battle in 'Fuyuki,' one participant, Kotomine Kirei, grapples with solitude and a quest for purpose. His enigmatic Command Seals lead him to Emiya Kiritsugu, a ruthless contender with an unwavering desire for the Grail's miracle. Set a decade prior to the events of Fate/stay night, this conflict sheds light on the intertwined destinies of Shirou's foster father, Rin's father, and the enigmatic Kirei, unveiling a compelling tale of ambition and revelation.