Eri Takabe is a Japanese first-year violin student at Shukusei Music Academy. Born into affluence as the daughter of the Takabe Group chairman and granddaughter of a major department store founder, she actively dislikes the "rich girl" label and aspires to an ordinary life. She possesses a strong sense of justice, balancing kindness with strictness. Her notably sharp intuition allows her to perceive threats others miss.

Physically, she has violet hair, typically styled in a ponytail with side strands, red eyes, and stands 1.55 meters tall with measurements of 83-59-89 cm. She is often seen in school attire—a pleated skirt, vest, and ribbon hair tie—or casual wear like pajamas and hoodies.

Within the dormitory, Eri's perceptiveness proves pivotal. She uncovers Shuusaku's infiltration and blackmail scheme targeting students, disrupting his plans by discerning his true identity and motives. This intervention provokes Shuusaku's vengeful retaliation, leading to intensified psychological and physical threats against her and other residents. Her role emphasizes resilience amid exploitation.