Kaoruko Tachibana serves as Sakon Tachibana's maternal aunt and works as an assistant police detective. She regularly joins Sakon on his travels, motivated by her enthusiasm for encountering attractive men and savoring local cuisine. Confident in her exceptional beauty, she demands Sakon call her "Kaoruko nee-san" instead of the traditional "obaa-san." Professionally, she prioritizes uncovering the emotional drivers behind crimes over dissecting alibis or murder techniques, leaning on Sakon’s logical prowess for those investigative elements. Her intuitive style diverges from his systematic methods, and she consistently defers to him for resolving case intricacies. Her dynamic with Ukon, Sakon’s puppet, sparks comedic friction—she retaliates against Ukon’s taunts or blunt comments by striking him. Though supportive in investigations, she embodies a "bumbling policeman" trope, habitually suggesting flawed theories or rash conclusions. This creates a narrative foil to Sakon’s precision and fuels playful exchanges, especially with Ukon. A brief arranged marriage subplot triggers a temporary shift in her demeanor, though its lasting implications remain unexplored.