Natsume Takashiro investigates violent, sudden, or suspicious deaths as a coroner. Her undisputed professional skill is matched by methods favoring indirect communication and ambiguous dealings. She maintains a professional connection with private investigator Reiji Tokisaka, first established during his police tenure. Reiji still seeks her critical case information but deliberately limits contact due to her habitual demand for unspecified compensation—referred to as "something"—in exchange for assistance.

She is identified as the older sister of Shuugo Takashiro. Visually, she possesses brown eyes and long brown hair reaching her waist, marked by a distinctive mole and an eyepatch. Her typical attire includes a dress, jacket, and gloves, frequently accompanied by a cigarette reflecting her smoking habit.

Natsume insists on formal address, requiring others to call her exclusively "Natsume-san." Her exchanges with Reiji extend beyond professional transactions; one documented interaction involved her demanding sexual favors as compensation, proceeding despite his objections and lack of consent.

Her name's etymology reflects seasonal and structural elements: "Natsume" combines "summer" (夏) and "eye" or "ogle" (目), while "Takashiro" derives from "tall/high" (高) and "castle" (城).