Based on the Fate/Kaleid Liner Prisma☆Illya 2wei! manga by Hiroshi Hiroyama, which is a spin-off of the Fate/stay night erotic visual novel by Type-Moon.

Unaired 13th episode released on the 7th DVD/BD.

By chance, Ryo has slipped from the 1980s into the future, and is trying to get back. In the interim, he's working for the police force of the future, solving cases by applying his unique and often comical approach. (Source: ANN)

The story begins when Ao opens a package that arrives at her doorstep. Inside the package is Gourai, a Frame Arms Girl: a small robot capable of independent movement. Gourai is a newly-developed prototype: a Frame Arms Girl equipped with an "Artificial Self," an advanced AI that gives her a personality. Ao is the only one that has activated her. Gourai begins to gather both battle data and emotions, starting a day-to-day life with Ao, who knows nothing about Frame Arms Girls. (Source: ANN)