Kaoru is a ninja and a member of the Shinobi 5, a mercenary ninja group for hire. She is familiar with Zenzo, and attended his father's funeral. She has been seen working in a flower shop into which Kagura crashed with scooter, damaging a flower-petal birthday present that was planned for Michiko, the wife of Kaoru's manager at another of her part-time jobs, the Kunoichi Café where also Ayame works.
Much like Sarutobi Ayame, Kaoru is often childish and playful, eg. when the two of them were supposed to fight during the Ninja Battle in the Elizabeth Rescue episode, but spent a long time just staring and trash talking each other. However, she gets serious when it comes to work.