Rio is an attractive high school girl of average height with light brown eyes, grey hair, and glasses. She is a member of the Science Club and is often seen in her school uniform and a lab coat. She has a slender yet voluptuous figure with a large bust, which is a source of significant self-consciousness and insecurity for her. Intellectually, Rio is intelligent and well-articulated. Her personality can come across as blunt, straightforward, and sarcastic, but beneath this somewhat cold exterior, she is kind, helpful, and supportive.