Hazuki Minase

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. Rin, who had been tasked by the wizard Zelretch to collect the seven Class Cards containing the spirits of Heroic Spirits from legend, finds that she is unable to change Ruby's mind and must supervise Illya in completing the task of collecting the Class Cards. 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.

A high school student named Yachi Haruaki receives a mysterious, super-heavy black cube from his father overseas. That night, Haruaki wakes up to a suspicious noise in the kitchen, and he discovers a fully naked female thief of rice crackers. The girl, Fear, is the first of several surprises that Haruaki receives.

Despite his adoptive father's warnings that the girl found in the remnants of a destroyed city is too dangerous to be considered anything other than a tool or weapon, Shirou Emiya comes to treat Miyu as a younger sister. But when Shirou relaxes his guard and Miyu starts normal school, the Ainsworth family and their agents swoop in, kidnapping the girl with the goal of sacrificing her! Faced with the realization that Miyu's ability to do good will always be equaled by her capacity for destruction, Shirou must attempt to both rescue his adopted sister, and decide how to confront the threat that her powers will always pose.

The world is dying, no longer able to support life. The Ainsworth family can use the Holy Grail to save humanity, but the price of salvation is sacrifice of the magical girl Miyu — but Miyu’s brother, Shirou, won’t let them have her without a fight. Now it’s up to Illya to step in and find a solution that will save not only Miyu, but the entire world for impending doom. But when the price for the world's salvation is the life of a single, innocent girl, what will Illya choose?

From a surreal talk show where a berserker hostess puts her hapless assassin brother co-host through an increasingly grueling wringer, to spicy ramen endurance tests, magical girls gone wild and wholesale gender-swapping for no apparent reason, you've never seen anything like Fate/kaleid liner Prisma☆Illya: Prisma☆Phantasm