TV-Series
Description
Miyu Edelfelt first appears in the second season of the anime as a young girl who was brought into the main world from a parallel world. She is later revealed to be a Child of God, a being with the innate ability to grant wishes, and she served as the complete Holy Grail vessel in her world of origin. After a catastrophic disaster devastated her hometown, she was found by Kiritsugu and Shirou Emiya from that parallel world. Kiritsugu adopted her with the intent of using her wish-granting power to save the world, but Shirou instead cared for her as a sister. Miyu eventually used her power to wish for she and Shirou to become true siblings, sealing away her divine nature. In the main world, she was taken in by Luviagelita Edelfelt, who adopted her as a younger sister. During the events of 2wei, Miyu lives in Luvia's mansion and acts as her maid. She wields the Kaleidostick Sapphire, which allows her to transform into a magical girl, and she is partnered with Illyasviel von Einzbern.

Miyu initially displays a mature, dutiful, and reserved personality. She takes her responsibilities as a magical girl very seriously and is unsociable, avoiding unnecessary involvement with others. She possesses advanced academic knowledge and physical strength, but her social and communication skills are underdeveloped due to a childhood spent in isolation. Her initial interactions with Illya are marked by a sense of superiority, as she has a much better command of her abilities than Illya does, and she treats Illya as a bothersome rival. However, Miyu's core motivation is a deep longing for genuine familial bonds. Her strongest driving force is her wish to be truly connected with her brother Shirou, which she eventually realizes through her wish. This longing extends to a desire for a meaningful friendship, which she gradually forms with Illya.

In the story of 2wei, Miyu continues her role as a magical girl alongside Illya. After the Class Cards are collected, the two are tasked with stabilizing ley lines, an operation that inadvertently causes Illya to split into two people, leading to the emergence of Kuro. Miyu's role expands as she becomes a key fighter against the Enforcer Bazett Fraga McRemitz, who attempts to take the Class Cards. Miyu fights Bazett using the Saber class card, demonstrating her capacity for serious combat. Later, she is captured by the Ainsworth family from another world, setting up the central conflict of the following season.

The most important relationship Miyu develops is with Illya. What begins as a rivalry based on Miyu's dismissive attitude toward Illya's perceived incompetence evolves into a deep, almost overwhelming friendship. Illya is Miyu's first true friend, and Miyu becomes intensely attached to her, often seeking her company and showing a protective, sometimes possessive affection. She also maintains a strong bond with her brother Shirou, the foundation of her sense of family. Additionally, she shares a complicated dynamic with Kuro, viewing her as a rival for Illya's attention, though they eventually cooperate in battle.

Miyu undergoes significant personal development throughout 2wei. She begins as a solitary girl who does everything alone, but her growing trust and friendship with Illya allow her to open up. Her intimacy with Illya increases dramatically, and she becomes emotionally reliant on Illya's presence. This relationship represents her first major growth beyond a life of solitude and duty. She later confronts trauma related to her past and the burden of her powers, becoming a more proactive character who takes ownership of her own fate.

Miyu's combat abilities are defined by her use of Sapphire, which provides her with a virtually unlimited supply of mana. She favors a direct, high-output combat style, using concentrated mana bullets, slashing attacks with mana shaped like blades, and powerful blasts. Unlike Illya, who can fly, Miyu moves by creating footholds of mana in the air, allowing for fast, linear movement. She also possesses the ability to install Class Card spirits. After witnessing Illya use the Saber card, Miyu becomes able to embody the Heroic Spirit Artoria Pendragon, gaining access to weapons like Excalibur. Her nature as a Child of God grants her the wish-granting ability of the Holy Grail, though this power is largely sealed after her wish to become Shirou's sister. In battle, she demonstrates high combat awareness and, through her willpower, can continue fighting even after receiving lethal wounds.