Fate/kaleid liner Prisma Illya 2Wei!: Magical Girl in Hot Springs Inn

Illya and her friends are heading off on a trip to the hot springs, a place to relax and recover their strength. But for Rin and Luvia, who come along supposedly to keep everyone safe, this trip is not just a relaxing getaway but a secret and risky mission. Meanwhile, Kuro, Illya's dark side, notices something alarming: the springs are draining her magical energy far faster than usual. This raises plenty of questions: what lies behind this phenomenon, and why are her abilities behaving so strangely?

Illya's story is that of a fifth-grade girl who unexpectedly became a magical girl with incredible power thanks to the world's mightiest magical staff. Aware of the danger her latent abilities posed, her parents had decided to seal them away to protect both their daughter and those around her. But when Illya came under attack, the seal gave way, and out burst Kuro, the dark, rebellious part of Illya herself, who gained a body of her own.

This OVA is based on the manga by Hiroshi Hiroyama, a spin-off of Type-Moon's Fate/stay night, and was bundled with the limited edition of the sixth volume of the Fate/kaleid liner Prisma Illya 3rei!! manga.