Having lost both her parents in a car accident when she was very young, Naoto is an orphan who acts very mature in spite of her age. As a descendant of a respected lineage of famous detectives, she wears formal clothing and deepens her voice when she speaks in a sophisticated, stilted manner. She is generally very serious, focused and mission-oriented. She rarely jokes around which can make her seem like a killjoy or party pooper when the team is involved in silly antics.