This story takes place at the end of the 21st century. Humanity has discovered a new type of energy called DG (Divine Grace) that has revolutionized the economy and space exploration. However, when settlers attempt to colonize Pluto, unidentified alien lifeforms known as “Nergal” suddenly attack and annihilate them.
To fight the Nergal, the United Earth Forces forms the AG Unit, which consists of ancient robots called “G’s Frames” that were excavated from ruins around the world. These robots are piloted by girls with special qualities who are known as “Ancient Girls.”
The 1st AG Unit is launched to protect the earth, and thus begins the first war between humanity and the Nergal. During the Jupiter Trojan Campaign, there are many casualties, and Reiu Minamiya, the pilot of the Unit No. 4 Asena, is missing-in-action afterwards.
Some time later, our protagonist, Reika Minamiya, volunteers to serve in the AG Unit to find her sister, Reiu.
This is a story of camaraderie, bonds with ancient robots, and a deadly battle with aliens.
The girls must overcome much hardship and grow as people and pilots.

“We’ll change the fate of the world! ...Before the earth is consumed.”