Rio Futaba, a second-year student at Minegahara, is an intelligent and articulate young woman with extensive knowledge of chemistry and quantum physics. She wears her school uniform and lab coat, with glasses, and has a slender yet voluptuous body with a large bust, which she dislikes. Despite her cold exterior and blunt demeanor, Rio is kind, helpful, and supportive, particularly in solving Puberty Syndrome cases, showing her sensitivity and insecurities about her early developed body.