Kaoru is a young girl who appears in Super Mario no Shōbōtai.
Kaoru is shown in the opening scene, taking turns playing Super Mario Bros. 3 with her brother Tatsuya, and expressing annoyance when he offered gameplay tips. Their mother comes in and asks Kaoru to pick up some groceries; as she prepares the list, Kaoru finds some sparklers in a kitchen drawer and takes them to show to her brother, planning to sneak away and set them off later.
Kaoru and Tatsuya are later seen in the auto junkyard, and she reassures her worried brother as they prepare the fireworks. Unbeknownst to them, Mario and Luigi are repairing a Jeep nearby. As they watch the show, Luigi notices smoke coming from a garbage can, where a stray ember had landed; the contents eventually catch fire, scaring Kaoru and Tatsuya. The Mario Bros. quickly put out the flame and scold the children for being careless and setting off fireworks without supervision and emergency measures, warning them about the "true nature" of fire. Kaoru and Tatsuya envision a massive skull-shaped flame, causing them to feel guilty and apologize. As the Bros. tell them both to head home, Kaoru ponders the fact that no one would believe she had actually met Mario and Luigi, and the group share a laugh about it.
Still later that evening, while Tatsuya is playing Super Mario Bros. 3 again, Kaoru shows no interest in the game, contemplating their earlier brush with fire. The children's mother notices and wonders what is troubling her; Tatsuya tries to comfort his sister by saying that the Mario Bros. were exaggerating, which only worries their mother further. The children's father then comes home, having gone on another rice wine binge, and the mother asks Kaoru to run a bath for him; despite her sass, Kaoru complies. As she leaves, she notices Tatsuya is about to tell their father about the fireworks and gives him a look that reminds him to keep quiet.
Suddenly, an earthquake hits the area, causing the family to panic. As Kaoru cuts the bath water, she notices the gas stove is still running and quickly asks her to turn it off. After the earthquake subsides, Kaoru soon notices that a fire has broken out in the apartment across the street and calls emergency services (119) immediately. She then joins her brother and the nearby crowd in cheering as firefighters - who are none other than the Mario Bros. - successfully rescue the people trapped inside. Once the fire is extinguished, the children run up to Mario and Luigi and tell them that they had taken their fire safety advice to heart.