Fate/kaleid liner Prisma☆Illya: Vow in the Snow

Synopsis

Despite his adoptive father's warnings that the girl found in the remnants of a destroyed city is too dangerous to be considered anything other than a tool or weapon, Shirou Emiya comes to treat Miyu as a younger sister. But when Shirou relaxes his guard and Miyu starts normal school, the Ainsworth family and their agents swoop in, kidnapping the g...