Universal Century 0071. Three years have passed since the escape from Side 3's Autonomous Republic of Munzo. Casval and Artesia, the orphaned children of Zeon Zum Deikun, have fled to Earth along with Jimba Ral and taken refuge in the household of Teabolo Mass. They now live quiet lives under the names Édouard and Sayla. However, they are once again being targeted by the evil schemes of the pursuing Zabi family... Meanwhile, Side 3 has been renamed the Autonomous Republic of Zeon. The Zabi family have seized power, and as they consolidate their system of control, they embark on the development of a new weapon called the mobile worker in order to resist the Earth Federation Forces.