HMX-17a "Ilfa" is an experimental maid robot developed by Kurusugawa Electronics. She operates on the "Dynamic Intelligence Architecture" software created by Sango Himeyuri. Physically, Ilfa stands 153 cm tall with a slim build, pale complexion, blue shoulder-length hair, and violet eyes. Her measurements are 85-56-82 cm (bust-waist-hips). She wears a distinctive maid uniform featuring a miniskirt, pleated skirt, puffy sleeves, a string ribbon tie, thigh-high stockings, and Mary Jane shoes. During testing, Ilfa volunteers to work at the home of Sango Himeyuri and her twin sister, Ruri. This decision causes friction with Ruri, who feels Ilfa is usurping her household role. Despite Ruri's initial hostility, Ilfa develops affection for her, crediting Ruri with helping her overcome her fear of the outside world and learn that human interaction is not frightening, marking significant emotional growth. In the OVA "ToHeart2 adplus," Ilfa is assigned to serve at Yūji's residence due to his preference for robot maids, an assignment facilitated by Tamaki Kousaka. This serves as a learning experience in adapting to human environments and social dynamics. Ilfa belongs to a series of experimental robots including siblings HMX-17b "Milfa" and HMX-17c "Silfa." She exhibits authority within this group, particularly towards Silfa. When Silfa struggles with extreme shyness and emotional instability, becoming reclusive, Ilfa intervenes to discipline her, demonstrating her more composed and responsible nature among the HMX-17 units. Her background connects to the broader HMX series legacy from Kurusugawa Electronics, which includes earlier models like HMX-12 Multi, positioning Ilfa as a later iteration in this line of humanoid maid robots.