Saint Seiya: Meiou Hades Meikai-hen
English title: Saint Seiya: The Hades Chapter - Inferno
Japanese title: 聖闘士星矢 冥王ハーデス冥界編
Type: OVA
Source: Manga
Episodes: 12
Status: Finished Airing
Aired: Dec 17, 2005 to Feb 6, 2007
Duration: 24 min per ep
Rating: PG-13 - Teens 13 or older
Studios: Toei Animation
Genres: Action, Adventure, Fantasy, Sci-Fi
Themes: Mythology
Demographics: Shounen

Seiya and the rest of the Bronze and Gold Saints who have survived the Sanctuary battle have entered the world of the Dead. They are fighting to get to Hades and defeat him. 

(Source: ANN)