Jamitov Hymem and Bask Om arrive at the Newtype Research Institute Headquarters located in Indiana of North America. They have come to observe the condition of the newly modified Cyber​​-Newtype, Subject GH-8N-281 known as Rosamia Badam, a girl who was orphaned by the colony drop on Australia during the opening days of the One Year War.

CDA tells the story of Colonel Char Aznable directly after the One Year War. He heads toward Axis after the battle of A Baoa Qu with the remaining Zeon forces, where he meets a 14-year old Haman Karn, who begins to fall in love with Char. Char must also deal with Colonel Enzo, who plans to restart the war with the EFSF.