Property concept: Spin-off of Fate/stay night with Illyasviel von Einzbern as the protagonist, living an alternate life as a school girl.
The series began in 2007 and has run several short-run series with each working its own progression and theme while tied to the larger work.
This will mark the third season of the property that deals with the alternate world setting from the Fate/stay night universe as written and illustrated by Hiroshi Hiroyama.
Sentai Filmworks has licensed the first three seasons and released the first series on DVD and Blu-ray in bilingual form.