Lily Aquaria, commonly referred to as Sister Lily, is a nun and caretaker at the church orphanage in Hage Village, the rural birthplace of Asta and Yuno. She was born into the Noble Realm, where she witnessed the severe discrimination based on magical ability that divided the Clover Kingdom. Deeply saddened by this injustice, she left her noble upbringing to become a nun, hoping to help bring equality to the kingdom. As the primary caregiver for the orphans of Hage, she raised Asta and Yuno from infancy alongside the priest Orsi Orfai, becoming a maternal figure in their lives. Her personality is gentle, patient, and nurturing, yet she possesses a firm side when discipline is needed. She is devoted to her faith and to the children under her care, and she consistently encourages Asta and Yuno to pursue their dreams despite their disadvantaged origins. Asta develops an infatuation with her and repeatedly proposes marriage, but she gently declines each time, explaining that she is a sister to everyone and sees him as a beloved younger brother. Lily is a capable water magic user, able to both attack and heal when circumstances demand it, although she rarely engages in combat under normal circumstances. Throughout the series, her role remains that of a supportive background figure, but she becomes significantly involved in the story when she is possessed by the devil Lucius Zogratis, who uses her as a vessel for the high-ranking demon Baalzebub, granting her access to space magic. This transformation places her in direct opposition to Asta and the other heroes, marking a major development in her character. Despite this, her core identity as a kind and selfless caretaker remains central to her portrayal.