Kazue Takanashi is the eldest of the Takanashi siblings. She is a thirty-one-year-old woman with a tall stature, brown hair typically tied in a ponytail, and brown eyes behind a pair of glasses. Her most distinctive physical feature is a beauty mark located just below the left side of her lips.

Kazue holds a professional career as a lawyer, a role she uses to her advantage in daily life by employing legal expertise and logical arguments to strengthen her position in any dispute. Her primary motivation stems from a deep-seated care for her family, which often manifests as stern enforcement of discipline. She is easily annoyed and frequently clashes with her younger sisters, Izumi and Kozue, scolding them for their self-destructive habits. While Kozue is depicted as a drunkard and Izumi as a reclusive writer who neglects her health, Kazue's frustration is rooted in genuine concern; she wishes to see them take responsibility for their own well-being. Unlike her relationships with Izumi and Kozue, Kazue is known to spoil her youngest sister, Nazuna.

In the story, Kazue is one of the four Takanashi sisters who have a significant, often stressful, impact on their younger brother, Souta Takanashi. As a supporting character, her appearances typically involve her visiting the family restaurant or interacting with the main cast, often leading to humorous confrontations based on her no-nonsense attitude. She is an authority figure within her family, primarily responsible for ensuring stability among her more eccentric siblings. Despite her harsh exterior, she demonstrates a softer side that reveals her deep worry for her family. An example of this is when her sister Izumi went missing; while she initially told Souta not to worry, she later showed her anxiety by shakily asking him for the number to call the police.

Throughout the series, Kazue's development is subtle but present. She is characterized as a divorcee, a fact that deeply offends her when mentioned, particularly by Izumi. Her history informs her current, no-tolerance approach to her sisters' life choices, as she believes in personal accountability. In terms of abilities, beyond her legal expertise which she wields in arguments, she is physically imposing and combines verbal skill with a readiness for violence to win disputes, a trait she often employs against those who ignore her viewpoint. She is largely responsible for managing the family's affairs and provides most of the household income through her career, highlighting her role as the family’s primary pillar of support.