Masumi Kamuro is a student at the Tokyo Metropolitan Advanced Nurturing High School, initially placed in Class 1-A and later as a second-year student in Class A. She has long purple hair tied in a ponytail and purple eyes, and she is a member of the art club. Kamuro is quiet, aloof, and socially withdrawn, with poor communication skills, little cooperativeness, and almost no close friends, which leaves her emotionally isolated. She is nevertheless very honest and loyal, having never acted against the interests of her class. Her academic and intellectual abilities rank at the bottom of Class A, but she excels in physical education, possessing a B+ physical ability rating. She is also physically strong, as demonstrated by her participation in the end-of-year basketball tryout. Kamuro has an obsession with the thrill of theft; early in her school life, she was caught shoplifting at a convenience store by Arisu Sakayanagi, who then forced her to become a subordinate. Since then, Kamuro has worked as Sakayanagi's most trusted enforcer, often called her "right arm." She handles intelligence-gathering and surveillance tasks, relying on her sharp instincts and cold, cynical demeanor. Her key relationship is with Sakayanagi, whom she willingly follows without question. Kamuro shows little personal development; she remains a steadfast tool within Sakayanagi's faction, fulfilling orders and protecting her leader's interests. Her notable abilities include her physical prowess, her talent for observation and stealth, and her complete loyalty, which make her an indispensable asset in the school's competitive environment.