OVA
Description
Illyasviel von Einzbern was crafted as the Holy Grail vessel for the fourth Fuyuki Holy Grail War, programmed at birth with necessary knowledge by the Einzbern family. Her parents, Kiritsugu Emiya and Irisviel von Einzbern, abandoned the ritual when she was eight months old. They sealed her magical abilities and related memories to grant her a normal life, though these persisted as a separate personality that later manifested as Kuro.

Raised in Fuyuki City alongside adopted brother Shirou Emiya under maids Leysritt and Sella’s care during her parents’ frequent travels, Illya lived ten ordinary years unaware of her heritage. She developed a cheerful, well-liked personality marked by shyness, an affinity for anime and cute objects like stuffed animals, a fondness for cats, and a fascination with maid outfits—though she disliked the traditional Einzbern attire. Magical Ruby often teased her about her subtle romantic attraction to Shirou.

Her life changed when the sentient Kaleidostick Magical Ruby, rejecting original wielder Rin Tohsaka, chose Illya as its master, transforming her into a magical girl tasked with collecting dangerous Class Cards. Initially reluctant and cowardly in combat, she teamed with rival Miyu Edelfelt (wielder of Magical Sapphire), forging a close friendship. A mission to stabilize Fuyuki’s ley lines caused a magical accident splitting Illya into two entities: her primary self and the darker Kuro.

Kuro, embodying Illya’s sealed memories and capabilities, initially sought to eliminate her original self. After confrontations, Irisviel revealed Kuro’s origin as the suppressed Holy Grail personality. To sustain Kuro’s form, Illya shared mana primarily through kissing, leading to Kuro’s integration into the household as Chloe von Einzbern. This dynamic pushed Illya to mature, embracing her role as Kuro’s "older sister" and protector despite Kuro’s teasing and mischief.

Facing threats like mage Bazett Fraga McRemitz—who attacked to reclaim Class Cards—Illya collaborated with Kuro and Miyu, using strategic traps and the Rider Class Card. Discovering an eighth Class Card (Gilgamesh) led to a temporary truce. Battles against Gilgamesh revealed Miyu’s origin as a parallel-world Holy Grail, prompting her kidnapping by the Ainsworth family. Illya vowed to save both Miyu and the Ainsworths’ world, demonstrating resolve to protect others at all costs.

Throughout adventures including hot springs and school festivals, Illya balanced magical duties with daily life. Her abilities expanded to flight, barrier magic, and Dual Wielding via Class Card Installations (e.g., Archer’s Kanshou and Bakuya). Combining Ruby and Sapphire unlocked Kaleido Liner Zwei form, granting cosmic wings and immense power at great physical risk. Despite growth, she retained childlike vulnerabilities like tantrums and embarrassment over her flat chest compared to Kuro’s physique.

Relationships deepened, particularly with Miyu, sharing a pseudo-romantic bond involving mutual protection and mana. She showed kindness to former enemies like Angelica, reflecting her core trait of seeking friendship over conflict. Across media, Illya evolved from a hesitant magical girl into a determined heroine committed to safeguarding loved ones and forging her own path.