Fate/kaleid liner Prisma☆Illya Movie: Sekka no Chikai
"I think I'm going to tell you about me and Miyu's story up to now."
The world's destruction progresses. The only thing that can stop it is Miyu's sacrifice that is worthy of the Grail. When Ainsworth asks Illya, the one who carries the title of the world's savior, what she will save between the world and Miyu, she chooses the simple and selfish answer of "both." In a respite from the fighting, they all rest in the house Miyu and Shirou took care of. When they gather in a circle, Shirou tells them about himself and Miyu. She was the Child of God that granted any and all wishes. Shirou took in the girl who had no one else into the household that he had shared with Kiritsugu. It has been five years since then, and now they have lived peacefully like siblings. But that peaceful everyday life has now been shattered. They will take her back, but before that, Julian makes his appearance, still seeking in Miyu the miracle that he needs.
The connection that lies between Miyu, Shirou, and Ainsworth will be told here.