A young woman named Sakura Matou, with the sins she has committed, drowns in the murky darkness. A young man named Shirou Emiya, who vowed to protect Sakura, works together with Rin Tohsaka and throws himself into the raging battle to put a stop to the Holy Grail War. Illyasviel von Einzbern, as one of the few who knows the truth behind the conflict, confronts her own fate, while Zouken Matou uses Sakura to try to fulfill his own desires.