Pegasus Tenma, King Hades, and the Goddess Athena and through the twist of their 3 fates merge together which unfolds a prologue to the original Saint Seiya.
TMS brought out the first series for Saint Seiya: The Lost Canvas streaming some time ago on the Amazon Prime Video the service.
The anime adaptation only covers about half of that series, which ran from 2006 to 2011 and is unlicensed in that form.
The anime release is DVD only and it will be in its original Japanese language with English subtitles as no dub was previously produced.