Ai Kisugi, the youngest and most tomboyish of the Kisugi sisters, channels her genius-level IQ into mechanical expertise, computer programming, and engineering. She designs specialized gadgets to aid her sisters' heists. Though physically the weakest sibling, she offsets this with exceptional agility and mastery of getaway vehicles—including helicopters, motorcycles, cars, and aircraft. Her appearance features short dark hair and brown eyes, with an orange catsuit as her mission attire and casual outfits elsewhere. She embodies typical teenage preoccupations, often daydreaming about romance, and cherishes her pet tabby cat, Tiger. Distinct traits include an intense phobia of snakes and no memories of her father, who vanished after her birth. Despite her technical brilliance, she occasionally errs during operations. Her sisters deeply trust her judgment, particularly in art appraisal. In *City Hunter: Shinjuku Private Eyes*, Ai appears with Hitomi and Rui in a crossover role. The trio dons their signature catsuits to assist Kaori Makimura in infiltrating a high-security building, with Ai parachuting alongside Kaori. Their return after a prolonged absence draws reverence from former employer Umibozu. When their café sustains damage during an attack, Ai and her sisters acknowledge Umibozu and Miki bear no fault. Her background remains consistent: she provides technical support, pilots vehicles in critical moments, and retains her energetic, youth-focused perspective.