The anime is set immediately after the main storyline's Sanctuary arc after the defeat of Gemini Saga from Masami Kurumada's original Saint Seiya manga, but before the Posieidon arc. However, whereas the original manga followed a boy named Seiya and other Saints who fight to protect the goddess Athena, the new series follows a female "Saintia" named Shō who fights evil deities to protect Athena.

(Source: Anime News Network)

 AnimeRulz is the best site to watch Saint Seiya: Saintia Shou SUB and DUB in HD quality.