Saint Seiya: The Lost Canvas

Probably the most underrated anime ever, Saint Seiya The Lost Canvas is a prequel to the original anime which is also known as Knights Of The Zodiac, and takes place in the 18th century. The story of the anime revolves around Greek Mythology, with Tenma, Alone and Sasha, three orphans living together with a strong friendship bond and protecting one another. Their fate separates them at a different age as Alone's sister, Sasha finds out that she is the reincarnation of Athena, Tenma becomes the Pegasus saint/knight and they eventually have to war against , Alone who is awakened as Hades, putting old friends into battle and triggering the new holy war.
Trailer for Saint Seiya The Lost Canvas