Megumi Minami, often called Megu by her friends, is one of the main characters in Class Q at the Dan Detective School. As the only female member of this special class, she stands out among her peers, who are considered the most promising candidates to become the successor of the legendary detective Morihiko Dan.

Prior to joining the Dan Detective School, Megumi studied at the Tokyo National Talent Development Research Center, where she was a classmate of Yutaka Saburomaru, a student who would later be placed in the higher-ranked Class A. At home, she lives in an apartment with her older sister, Akane, who attends a local university, while her parents work overseas.

Megumi possesses the rare and powerful ability of photographic memory, sometimes referred to as "Shunkan Kioku" in Japanese, which allows her to instantly memorize and recall every detail of a scene. This gift makes her an invaluable asset during investigations, as she can notice if a single piece of evidence has been moved or is missing, and she can recreate crime scenes with perfect accuracy. However, this ability also carries a significant drawback. She cannot selectively forget anything, meaning she is permanently haunted by the gruesome and disturbing images she witnesses, such as the sight of a corpse at a crime scene.

In terms of personality, Megumi is generally a kind-hearted and caring individual who looks out for her fellow classmates. She often finds herself acting as the voice of reason, keeping the boys in Class Q in check. Despite her good nature, she can be quite sensitive and has a short temper, easily losing her cool at the antics of her friends, particularly Kyu, who has a running joke of accidentally glimpsing and announcing the pattern of her underwear.

Megumi plays a crucial role in the story, often providing the key piece of evidence needed to solve a case. Her journey is not just about becoming a better detective but also involves personal and emotional development. Her motivations are initially driven by a desire to use her gift to help others, but she is also shown to be a dedicated student who experiences the same pressures as her peers, such as the stress of meeting the high expectations set by their mentor, Morihiko Dan.

Her key relationships with her male classmates are a central part of the narrative. She is close friends with Kyu, the protagonist, who is optimistic and has a natural talent for logical deduction. Kyu is often the one to help calm her nerves, and a strong, mutual affection grows between them over time. In one notable instance, Kyu disguised himself to help her solve a difficult homework problem, and Megumi was deeply touched by his act of kindness, keeping the money he used as a personal charm. Similarly, her relationship with the brilliant and mysterious Ryu is complex. Megumi initially develops a crush on him, often blushing when he is near. It is later revealed that this is because they met when they were very young, but a criminal organization called Pluto, to which Ryu is connected, erased her memories of that encounter. As the story progresses, her feelings for Kyu become more prominent, and she starts to blush when he is around as well, ultimately leading to a romantic resolution with him in the finale of both the manga and the anime. Despite being the only girl in her class, she also forms friendships with female students from Class A, such as Sakurako Yukihira and Kuniko Touya.