In ancient times, the Titan Cronus (son of Uranus the sky and Gaia the earth) and his wife Rhea gave birth to six children. Five of them were swallowed by Cronus, and only one was saved, Zeus, hidden from Cronus by Rhea. Upon reaching adulthood, Zeus forced his father to vomit the other five gods. Zeus, along with his brothers and sisters, decided to battle the Titans for control of the universe. Cronus and the other eleven Titans lost the battle and were sent to Tartarus.

Thousands of years later, in Greece, the Pope visited the room of the recently reincarnated infant Athena, with a golden dagger.

Before he can kill her, the Gold Saint Sagittarius Aiolos saved her, and unmasked the Pope. Aiolos, horrified, fled. The Pope then declared him a traitor to the Sanctuary, and had Capricorn Shura murder him.

This caused his younger brother, Leo Aiolia, to grow under the shadow of his "traitor" brother, suffering from all manner of abuse and scorn.

It left him with a grudge against the Gold Saints and Sanctuary as a whole, which caused the Pope and most of the Sanctuary to distrust him.

To make things worse, the enemies of Zeus, the Titans, were revived and began to seek vengeance against him and the Sanctuary. This marked the start of Aiola's story and the battle of the Gold Saints against the Titans.

Episode G is set 7 years before the events at the beginning of the original Saint Seiya Manga, and 6 years after the death of the Gold Saint Sagittarius Aiolos.