Eri Kisaki is the legally separated wife of private detective Kogoro Mouri and the mother of Ran Mouri. A highly accomplished lawyer, she runs her own successful practice and is widely feared and respected in her profession, earning the moniker Queen of the Courtroom. Eri and Kogoro were childhood friends who fell in love during their teenage years. Their separation, which occurred about ten years before the main storyline, is a source of frequent misunderstanding. Ran once believed her mother left because Kogoro shot her in the leg to save her from a crazed serial killer; in truth, Eri respected that decision. The actual reason for their split was far more domestic: after the incident, Eri cooked Kogoro a gratitude dinner which he bluntly criticized as being completely inedible, leading her to leave him and focus entirely on her legal career.

In terms of personality, Eri is incredibly intelligent and possesses a sharp, analytical mind with an eye for detail, which makes her an invaluable asset when investigating crimes. Her demeanor suits her occupation; she is questioning, logical, and often inserts herself into investigations alongside Kogoro, much to his annoyance. Despite her tough exterior and frequent arguments with her husband, particularly over his drinking and flirtatious habits, she still deeply loves him. She frequently tests him to see if he still cares for her, and their daughter, Ran, often schemes to get them back together. Eri maintains a close friendship with her secretary, Midori Kuriyama, and is also close friends with Yukiko Kudo, a rival from their high school days.

Eri's role in the story is that of a supportive, if distant, parent and a capable ally in solving cases. She often serves as an extra pair of eyes during investigations and her deductions are almost always accurate. She views Conan Edogawa as a remarkably intelligent child and sometimes facilitates his deductive displays. Ran frequently goes to her mother for advice, especially regarding her relationship with Shinichi Kudo, to which Eri half-jokingly responds that the best advice is never to get involved with a detective.

Regarding her abilities, beyond her legal expertise, Eri is highly skilled in judo, a martial art she learned from Kogoro. She has been shown capable of subduing assailants using techniques like the ippon seoi-nage (one-arm shoulder throw). However, she has one notable weakness: her cooking is notoriously terrible, a trait she remains largely unaware of despite it being a primary cause of her marital separation. She is also a cat lover, owning a Russian Blue named Goro, who she named after her husband because of their similar personalities.