7th Dream Poor Sakura Vol 4 37 1 -

—a mysterious entity intent on forcing Kotomine to continue the war for the 8th Grail. The Black Stone:

As Sakura dangled over the thousand-foot drop, her fingers slipping against the cold rain-slicked metal, she looked up. Unit 1 stood over her, its visor shattered to reveal a face—not a robot’s, but a mirror of her own. 7th Dream Poor Sakura Vol 4 37 1