Motoko Tsutsumi is the younger sister of Moriya Tsutsumi and a graduate student enrolled in the school of robotics engineering at Nerima University. She shares her brother's academic background but maintains a distinct and more lighthearted personality. Motoko is known for her playful and teasing nature, often enjoying banter with those around her. Despite living on her own, she exhibits a somewhat pampered or princess-like demeanor and frequently returns to her family home whenever she grows tired of her solitary routine. Her motivations are not driven by grand ambitions but rather by personal interest and social connection. She develops a noticeable romantic interest in Hiroshi Ochanomizu, one of the central researchers involved in the development of the artificial intelligence known as Bewusstsein and the robot A106. This interest draws her further into the orbit of the main characters and the events surrounding the robotics laboratory. In the story, Motoko serves as a supporting character who provides both emotional warmth and occasional comic relief. Her relationships are defined primarily by her bond with her brother Moriya and her affectionate pursuit of Hiroshi. She does not possess any special combat or technical abilities that set her apart as a researcher; her role is more that of a spirited observer and a source of interpersonal dynamics among the cast. Throughout the series, she remains a consistent presence whose personality helps to balance the more intense or serious elements of the plot, though her development is largely limited to her personal connections rather than involvement in the central scientific or conflict-driven arcs.