Fate/kaleid liner Prisma☆Illya: Vow in the Snow

Kiritsugu sees Miyu as a tool because her power to grant wishes unconditionally makes her the key to saving humanity from destruction. Since humanity's survival depends on using her abilities, he prioritizes her utility over her individuality. However, Shirou rejects this view and forms a genuine bond with Miyu despite Kiritsugu's warning.

The storm was triggered by the thoughts and desires implanted in Miyu by humans. Since she possesses the power to grant wishes unconditionally, exposure to human thoughts and desires created a magical upheaval that manifested as the storm ravaging Fuyuki city.

Julian Ichigi belongs to the ancient Ainsworth mage clan who foresaw humanity's end. He needs Miyu as a sacrifice to ignite the Fifth Holy Grail War, intending to use the Grail's power to avert humanity's destruction. Her wish-granting ability makes her the perfect catalyst for the ritual.

The Ainsworths are an ancient mage clan who foresaw humanity's destruction. Their goal is to seize the Holy Grail and use its power to prevent humanity's end. Julian Ichigi is a member of this clan pursuing the Fifth Grail War to achieve this objective.

Shinji Matou was revealed to be a puppet under Julian's control. During the confrontation with Shirou, Shinji attacked them wielding the Assassin Card, and when defeated, it became clear he had been magically controlled by Julian as part of the latter's scheme to eliminate potential obstacles.

Shirou chooses to use his wish to send Miyu to a different world where she can find happiness, even though this defies Kiritsugu's original plan to use her power to save humanity. He prioritizes Miyu's personal happiness over the heroic ideal his father wanted him to pursue.

The Servant Cards are magical cards that grant their holders the abilities of Servants from the Holy Grail War. Characters like Sakura and Angelica possess these cards (Archer Card, Assassin Card), allowing them to use powerful abilities. Julian manipulates the holders as puppets throughout the war.

Sakura is killed during Shinji's attack while accompanying Shirou. Shinji, under Julian's control as a puppet, attacks them with the Assassin Card. Sakura dies in the skirmish, though she had previously confessed her feelings for Shirou and offered to help rescue Miyu.

Miyu is transported to an alternate Fuyuki after Shirou's wish completes the ritual. She wakes up in this new world with a determined goal: to search for the remaining magical cards that grant wishes and chart her own path toward happiness, separate from her adoptive family.

Shirou defies Kiritsugu's original plan because he cannot accept treating Miyu as a mere tool for humanity's salvation. Instead of using her power to save the world, he chooses to prioritize Miyu's personal happiness by sending her to a world where she can live freely, even at the cost of leaving himself alone.