Midgard

Midgard (ミッドガルド, Middogarudo) is a heavily disguised God Warrior whose real identity is uncovered by Dragon Shiryu (Cygnus Hyoga, who had been brainwashed by Drbal). He appears as a minor antagonist in "Saint Seiya: The Heated Battle of the Gods".

Overview
When Athena, Frey, Freya, and the Bronze Saints go down the stairs of the palace of Valhalla, Midgard, Uru and Rungu stand in their way. They do not move when Frey orders them to depart, with Midgard blocking Shiryu's way. After a while, he moves aside with the order of Loki, though not before Shiryu feels a very familiar Cosmos from him.

Later, Midgard intercepts Shiryu in a forest while the latter is on his way to save Athena, in the process being prompted to take off his helmet and mask, revealing his true identity, Hyoga. He then uses his freezing powers to immobilize Shiryu when the Dragon Saint approaches and tries to greet him, proceeding to throw the other into the air and hit the other repeatedly. He meets no resistance, as Shiryu does not consider Hyoga an enemy but rather considers him a friend. As "Midgard" continues attacking, Shiryu asks him for the reason why he's acting that way, and "Midgard" reveals that when he came to Asgard, he realized that Odin was the most powerful god, surpassing even Athena--and that the God Warriors were the most powerful warriors, surpassing even Athena's Saints. Those were the reasons that he decided to become one of the holy warriors serving Odin.

After falling into a lake, "Midgard" freezes the water and prepares to deliver the coup de grâce to Shiryu, who is still determined to return his friend to normal and prepares his Rosan Shoryuha. After they clash, "Midgard's" God Robe is destroyed and Shiryu, filled with regret, falls below to the frozen waters.

Trivia

 * Midgard is the term in Norse mythology for Earth, the world of men. The word means "Middle Enclosure", as Earth was at the center of the World Ash Tree, Yggdrasil (which represented the universe and from which the nine worlds of Nordic myth hung suspended).
 * It is fitting that Hyoga, as the Cygnus Saint, briefly ended up as one of the God Warriors, as they are based on Nordic/Germanic myth and Wagnerian opera. In Germanic myth, there is a legend about a swan knight, usually named Lohengrin (Loherangrin), who arrives from nowhere in a boat drawn by the graceful birds to protect a maiden in danger of losing her inheritance. He soon marries her, but in return for his services, he asks that she never ask his real name. Ultimately, his bride is persuaded to ask the forbidden question; the swan knight reveals his name and his position as a knight who guards the Holy Grail but, due to the wife breaking her promise, he has to now leave her (in some variants, this is because a Grail Knight is forbidden to do good deeds unless they are done anonymously, as per the virtue of Humility). He steps back into his swan boat and departs, never to be seen again. This legend was adapted by the composer Richard Wagner into the famous opera Lohengrin.