Kaneko is a notable recurring character in Mysterious Joker, best known for her unwavering loyalty and formidable presence as the secretary to the wealthy and antagonistic Mr. Kaneari. Her primary role in the story is to serve her master and assist in his elaborate schemes to capture the phantom thief Joker. She is depicted as a devoted and hardworking assistant who actively sets traps and waits for opportunities to ensnare Joker and his partners, making her a consistent obstacle for the protagonists.

While her duties to Mr. Kaneari define her professional life, Kaneko possesses distinct personal traits that add depth to her character. She has a known hobby of collecting glasses and a particular fondness for a snack called Mr. Cookie, which is baked in the shape of her employer's face, further underscoring her devotion to him. Her appearance is distinctive, and the series occasionally plays with her design; for instance, the main character Joker once used a special "Image Gum" to disguise himself as her. Her real name is revealed to be Commando Satsuko, a detail that hints at her true nature.

Kaneko's personality is marked by her serious and dedicated demeanor in her role as a secretary and enforcer. However, the narrative also uses her in comedic and action-oriented situations that showcase a more volatile and powerful side. She is known to possess tremendous physical strength, which she demonstrates in various episodes. In one instance, she showcases her power by protecting Mr. Kaneari's property, and in another more extreme example, she carries him on her back while running down a highway. One of the most revealing episodes involves an accident at a hot spring where Joker inadvertently touches her, and she is subsequently hit by Cupid’s Arrow, causing her to fall obsessively in love with him. This leads to a chaotic sequence where she relentlessly pursues Joker, driven by the magical infatuation.

Her key relationships are central to her development. Her absolute loyalty to Mr. Kaneari is her primary motivation, and she serves as his most trusted subordinate. As an antagonist to the main cast, she is a direct rival to Joker and his partner Hachi. Her role as an adversary is significant enough that she is consistently listed alongside the police as a major recurring challenger. Her capabilities as an antagonist are further demonstrated when she temporarily allies with the evil organization Devil Fang to capture Joker, although this collaboration ultimately fails and leads to her expulsion from the group by its leader, President D. Despite her failures, she remains a formidable and determined figure in Kaneari's employ, showing little significant change in her core loyalties throughout the series. Her most notable development comes from the temporary personality shift caused by the Cupid’s Arrow, which reveals a dramatically different, love-struck side to her usually serious character.