Miyuki Nanase is the childhood friend and next-door neighbor of Hajime Kindaichi, the protagonist. She is a diligent and academically outstanding high school student, often seen balancing her responsibilities in the student council and various clubs. In the anime adaptation of the Black Magic Murder Case, Miyuki accompanies Hajime to the Grape Manor in Karuizawa after his old friend Izawa Kentaro requests his help in investigating the death of the company president. Her role in the story is primarily that of a supportive companion, providing emotional stability and practical assistance as Hajime navigates the complex web of secrets surrounding the Hi matsuri family. While she does not take a leading part in the deduction, her presence is a constant anchor for Hajime.

Her personality is marked by a sense of responsibility and a caring nature. She is often exasperated by Hajime’s lazy tendencies but remains fiercely loyal and protective of him. Her motivations stem from her deep affection for Hajime, a bond that has existed since childhood, and a genuine desire to see justice served. Although she is not a brilliant detective like Hajime, she possesses sound judgment and a strong moral compass, sometimes noticing subtle clues or offering helpful observations.

Key relationships include her lifelong friendship with Hajime, which is characterized by mutual affection that neither fully admits aloud. She also interacts respectfully with Inspector Kenmochi and other recurring characters. In this particular case, she is a supportive figure rather than a central driver of the plot. Over the course of the story, she remains consistent in her role, showing no major personal transformation within this arc but reinforcing her importance as Hajime’s closest ally. Her notable abilities lie in her organizational skills, her empathy, and her ability to remain calm under pressure, all of which contribute to the group’s efforts to uncover the truth.