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.

Suletta Mercury leaves her planet and enters the Asticassia School of Technology at the behest of her mother. There, right and wrong are determined through duels between students, and the top-ranking duelist will receive Miorine Rembran as their fiancée—this prize being decided by Miorine's father. When Guel Jeturk, the best pilot in school and Miorine's current fiancé, demands that his betrothed move in with him, Suletta disapproves, so Guel challenges her. Although she emerges as champion, Suletta is subsequently detained on suspicion of piloting a forbidden type of mobile suit—a GUND-ARM, or Gundam—which results in her victory being voided. Miorine refuses to accept any more injustices and proposes another duel with even higher stakes. Now, Suletta must triumph a second time, otherwise she will be expelled and the Gundam Aerial that means so much to her will be destroyed.

In the year Cosmic Era 0071, a wartime brawl between two mobile suits results in the destruction of a neutral country. Shinn Asuka finds his entire family killed as casualties of the violence, and swears his life toward a vengeful pursuit of the Earth's Natural forces, under the impression they were the ones responsible for his family's death. Shinn works his way up through the ZAFT military forces, eventually gaining access to the cockpit of the prototype Impulse mobile suit. Athrun Zala, a veteran of the recent war employed in the service of diplomat Cagalli Yula Athha, finds himself drawn into a new conflict between the Naturals and the Coordinators: human beings artificially enhanced before birth and hated by the Naturals for their biological advantages. As the new war rears its head and violence becomes inevitable, Athrun finds himself as a mentor to the bitter Shinn. Athrun must steer the young pilot towards a mindset of mercy before his rage and desire for vengeance consumes him.

Shortly after being rescued off the Himalayas, Federation Ensign Shiro Amada is accused of espionage due to his encounter with Zeon's top-secret mobile armor. Intelligence officer Alice Miller is assigned to investigate on Shiro's whereabouts during his disappearance. Her documented findings will determine whether or not Shiro is a traitor, and what his fate will be as commander of the 08th MS Team. (Source: ANN)