|Appears in:||Fate/kaleid liner PRISMA☆ILLYA|
|Japanese VA:||Kaori Nazuka|
|English VA:||Caitlynn French|
Miyu is the complete Holy Grail from the world in which the Class Cards originated. Her brother is that world's version of Shirou. Brought to the main world through unknown means, she was taken in by Luvia in her search to rival Ilya and Rin's partnership.
She takes her duties as a Magical Girl very seriously and is initially dismissive of Illya's abilities, but gradually warms up to Illya. She comes to value Illya's friendship greatly and is highly protective of her. She shows another side of her personality only when she is around her brother, were she behaves like the young girl she actually is.
Miyu takes on the Edelfelt name after being taken in by Luvia. She lives in Luvia's mansion and acts as her maid to earn her keep. She uses Ruby's sister Kaleidostick, Sapphire, in order to transform, and she initially has a much better understanding of her abilities than Ilya. She takes her role very seriously and treats Ilya as a bothersome rival, though they eventually become close friends. She later gains the ability to use the Saber class card to embody the Heroic Spirit after seeing Ilya perform it.
Miyu continues to fight as a Magical Girl, dealing with the mysterious 8th Class Card. After dealing with Illya's split personality, Kuro, Miyu and co. fight the Enforcer, Bazett. They defeated Bazett and cooperated with her to capture the 8th Card.
The 8th Card was revealed to come from another Holy Grail ritual, and it gains physical body, child Gilgamesh. Later it was revealed by Gilgamesh that she comes from a parallel world and she is a princess. After saved from black Gilgamesh by Illya, Miyu was captured by Angelica and Beatrice from another world.
Captured, Miyu is held captive in Ainsworth's stronghold.
Later it was revealed her original name was Miyu Sayutsuki (美遊朔月). She was a "Child of God", a child from an occult religion that worships children below 10 years old as gods, and this granted her wish-granting power, not unlike the Holy Grail. Kiritsugu and Shirou found her in an incident that brought her hometown into enormous black fire, and witnessed Miyu dispel the fire. Kiritsugu took her, wishing to utilized her wish-granting power to save the world.
Kiritsugu asked Shirou to use Miyu to grant his wish of world salvation, but Shirou couldn't do it because Miyu became more human each day. Kiritsugu died some years later, and Shirou continued to taking care of Miyu. At this time, Shirou and Miyu became really close. Miyu then use her power to wish for her and Shirou to become real siblings.
As a Magical Girl, Miyu is able to utilize the Mystic Code Kaleidostick, Sapphire, to tap into mana from parallel worlds and gains virtually unlimited mana. She also can utilize Class Cards; Including them to provide her Heroic Spirit's Noble Phantasm and Installing them to gains Heroic Spirit's abilities.
As a Child of God, she can grant a wish, however grand it is. But, this power is disappeared when she is 10 years old.