On the Other Side of Lies and Facade
Miyu and Kuro have an intense battle before Illya arrives to try and stop them, apologising for the words she said before. When Irisviel suddenly arrives to pick Illya up, Kuro tries to attack her, but she stops her with her own magic. Irisviel reveals Kuro was sealed away so that Illya can become the Holy Grail, with Kuro becoming upset when she learns the Holy Grail War no longer takes place, feeling she has no place to belong. She ends up overusing her mana and starts to disappear, but Illya gives her some of her own mana so that she can last longer. Told by Illya to make her own wish come true, Kuro wishes to have a family, allowing her to come back into existence as a proper member of Illya's family.
Aired 14/08/2014EP 6 - On the Other Side of Lies and Facade

Fate/kaleid liner Prisma☆Illya 2wei!
With great powers come great responsibilities, and that includes cleaning up the aftermath of your previous adventures. Which means that, instead of getting a break after saving the world, newly changed magical girls Illya and Miyu have to help deal with the side-effects caused by the sealing of the Ley Cards. Still, that shouldn't be too hard, right? Wrong! Not only are the ley lines failing, but to make matters worse, Illya somehow ends up with a magical clone… and that sinister clone has plans of her own! Worse yet, since the "dark" version of herself is drawing its power from the same source as our heroine, Illya's own powers are being reduced proportionately. These are definitely not the kind of problems that the average girl should have to deal with.
(Source: Sentai Filmworks)