"Because I've decided to become Sakura's ally of justice." The boy can no longer escape the truth—this is to save the girl and to uphold the justice he has chosen. The "Holy Grail War," waged by mages (Masters) and heroic spirits (Servants) over the wish-granting "Holy Grail," has become distorted. Matou Sakura sinks into endless darkness, burdened by the sins she has committed. Emiya Shirō, who vowed to protect Sakura, throws himself into brutal battles alongside Tōsaka Rin to bring an end to the Holy Grail War. Meanwhile, Illyasviel von Einzbern, who knows the truth behind the war, also steps forward to face her own destiny. "So, grit your teeth, Sakura." As the boy resists the storm and challenges fate, will his wish reach the girl? The final battle of the "Holy Grail War," now reaching its conclusion, is about to begin!