Lucy Webster is a student at the College and the roommate of Chise Hatori. She is the last surviving member of the Webster family, her brother having been cast out before the rest of the family was slaughtered in an event sometimes called the Webster Tragedy. The Webster family were a prestigious magical line known as book-spinning spiders, a tradition of weaving paper and books using spiders, and Lucy inherits that magical craft.

Lucy is a teenage girl with long, dark hair and black eyes. When in class she ties her hair up. She tends to be cynical when it comes to the notion of friendship, likely because of something that happened in her past. Despite this, she is not outright hostile to Chise; she helps her on occasion and remains observant of her. Lucy's guarded personality stems from her traumatic history, and her motivations are deeply tied to her family's legacy and her survival. She initially keeps others at a distance, but her role in the College arc involves forming tentative bonds, especially with Chise, as they share living quarters and navigate the challenges of the magical college together. Her key relationships include her connection to the Webster family's tragic past and her developing trust in Chise. Over the course of the story, Lucy shows subtle growth, becoming more open and willing to accept help and companionship. Her notable abilities revolve around spider-based magic, including the spinning and weaving of enchanted paper and textiles, a skill unique to her lineage.