It is a direct sequel to Kurumada's manga series Saint Seiya, while also serving as a prequel to the events presented in it.

The main plot is set in the 18th century during the previous "Holy War" between the Earth Goddess Athena and the Underworld God Hades, and centers on the battles between each deity's warriors who are known as the Saints and the Specters, respectively, during that era.

During the battle, Hades, the god of the Underworld recognizes Seiya as the feared enemy he faced millennia ago, in the ages of myth, reincarnated in this era.

As Alone became possessed by Hades, Tenma ventures to rescue him, meeting Aries Shion and Libra Dohko and eventually suffering defeat at the hands of two of the Magnates from the Underworld.

Surviving the encounter, the Saints return to Athena's Sanctuary to devise a strategy to prevent Hades from completing his machinations.

The current incarnation of Athena, Saori Kido, decides to save Seiya and is accompanied by the Saint, Andromeda Shun.

[3] Saint Seiya: Next Dimension was conceived by Kurumada as a prequel to his Saint Seiya manga, parting from elements revealed in it but never further developed and explored then, hence, he started writing and drawing Next Dimension by opening the storyline in a prologue, with a flashback to the last battle of his original manga, contained in the 28th volume.

In the first tankōbon volume, Next Dimension was confirmed to be canonical within the universe and chronology conceived by Kurumada for Saint Seiya.