Armaroid Lady originates as Princess Emeralda, a human rebel leader on Emeraldas opposing the tyrant Giros. Captured, she underwent an experimental procedure intended to crush her rebellion, transforming her into an Armaroid—a mechanical being composed of lethal live metal—resulting in the loss of her human body and memories. Cobra's time travel to her past during "Cobra The Animation: Time Drive" revealed their former romantic bond. Inspired by the future Cobra, the human Emeralda consciously chose the Armaroid conversion to gain the superhuman strength necessary for survival and continuing her fight against Giros.

Post-transformation, she became Armaroid Lady, Cobra's advanced android partner utilizing ancient Martian technology. She serves primarily as the skilled pilot of their spaceship, the Tortuga, possessing superhuman strength but rarely engaging directly in combat. Her strategic mind and piloting expertise are vital assets aiding Cobra against threats like the Pirate Guild. As Cobra's steadfast partner, they operate with deep, unspoken trust and mutual reliance. Her journey from human rebel leader to mechanical ally underscores her resilience and enduring commitment to justice.