On the planet Mercury, the advanced technology of cybernetic prostheses has led to the development of giant pilotable robots. However, prolonged use of these achievements in bioengineering takes a significant toll on a pilot's body. As the Merucians' mobile suits gain formidable power, fear rises among the people of Earth. On her daughter Ericht's fourth birthday, pilot Elnora Samaya tests the state-of-the-art Gundam Lfrith under the watchful eye of its creator, Cardo Nabo. Ericht visits Elnora at work despite orders not to, and chaos unfolds after she forms a strange bond with her mother's mecha.