Fate/kaleid liner Prisma Illya (Fate/kaleid liner プリズマ☆イリヤ, Fate/kaleid liner purizuma iriya) is a Japanese manga by Hiroshi Hiroyama (KALMIA). The series is serialized in Kadokawa Shoten's Comp Ace magazine from 2007 to 2008 where its anime adaptation followed. A sequel series titled Fate/Kaleid liner Prisma Illya 2wei! (Fate/kaleid liner プリズマ☆イリヤ ツヴァイ！) was serialized from 2009 to 2012, followed by a third sequel entitled Fate/Kaleid liner Prisma Illya 3rei!! (Fate/kaleid liner プリズマ☆イリヤ ドライ！！) began serialization in 2012.
The anime expanded into 4 seasons each adapting the manga series while the first three are licensed by "Sentai Filmworks". The first season for the first sequel aired between July and September 2013. The second and third seasons for the 2wei sequel between July and September 2014 and 2015 respectively. The fourth season for the 3rei sequel between July 6, 2016 – September 21, 2016.
A video game adaptation titled Prisma Illya (プリズマ☆イリヤ), was published by Kadokawa Games for Nintendo 3DS and released in Japan on July 31, 2014. A film entitled Fate/kaleid liner Prisma Illya: Oath Under Snow has been released in Japanese theaters on August 26, 2017.
The series is an alternate universe spin-off of the original Fate/Stay Night novel, with Illyasviel von Einzbern as the main protagonist along with various other characters from the series and its sequels and spin-offs.
Illyasviel von Einzbern is an ordinary elementary school student who becomes a magical girl when the magical Kaleidostick Ruby deems her a more suitable master than the sorceress, Rin Tohsaka. Unable to change Ruby's mind, Rin must supervise Illya as they are both tasked by the wizard Zelretch to collect the seven Class Cards containing the spirits of Heroic Spirits from legend. During Illya's adventures, she receives a friend and rival in a girl named Miyu, the contracted master of the Kaleidostick Sapphire, which similarly abandoned its original master and Rin's rival, Luvia Edelfelt.
After a series of battles, Illya and Miyu were able to collect all the Cards and became good friends, while Rin and Luvia remained in Japan by the order of Zelretch. However, the appearance of Kuro, a girl with a striking resemblance to Illya, soon complicates their lives as she attempts to eliminate Illya.