Miyuki Nanase is Hajime Kindaichi's childhood friend and next-door neighbor. A 17-year-old honors student at Fudo High School, she excels academically and exhibits a responsible nature. Her steadfast friendship with the often unmotivated and lazy Kindaichi puzzles peers, though Miyuki firmly believes in his underlying intelligence. She carries unspoken romantic feelings for him, subtly influencing their dynamic.

She frequently joins Kindaichi during investigations, offering support and occasionally participating in solving cases. While not matching his deductive skill, Miyuki demonstrates logical reasoning and perceptiveness. Once, when Kindaichi was hospitalized, she assumed the role of primary investigator to solve a murder, proving her capacity for independent problem-solving. Her role often involves providing emotional stability and practical assistance, reinforcing her position as a trusted ally. Her birthday is November 24.

During a high school trip to Hong Kong for a fashion event, she is explicitly referred to as Kindaichi's girlfriend. Mistakenly kidnapped there, she triggers a separate criminal investigation, highlighting both her vulnerability and her significance to Kindaichi's motivations.

Twenty years after high school, Miyuki becomes a flight attendant. Despite this career shift, she maintains communication with Kindaichi via mobile phone, indicating their enduring relationship.

Across manga, anime, films, OVAs, and live-action dramas, her core traits remain consistent. She is portrayed as compassionate and morally grounded, acting as a counterbalance to Kindaichi's impulsive tendencies. Her interactions with him blend concern, encouragement, and unspoken affection, contributing to their stable partnership amid investigations. Her character design and narrative function persist without substantial evolution; she embodies steadfast loyalty, emotional support, and intellectual reliability.