In 2042, alien threats known as the Mimetic beasts (擬態獣, gitaijū) laid waste to Japan. During a final battle against the Mimetic beasts, Goh Saruwatari defeats the alien "boss" and saves his future wife, Anna
Aoi, with his robot called Godannar. Now, on their wedding ceremony, the Mimetic beasts emerge after five
years of tranquility. Goh and Godannar are called to action, forcing Goh to leave Anna at the altar.
As Goh struggles in his battle against the Mimetic beast, Anna stumbles upon a sealed robot known as Neo Okusaer. She is able to activate and pilot the Neo Okusaer to save her "husband" by merging it with Godannar to activate the Godannar's Twin Drive. During the course of the series, it is discovered that humanity is threatened by a virus which is spread by the Mimetic beasts. All of humanity is infected, but the virus affects the Godannar pilots most
severely, since they come into close contact with the Mimetic beasts on a regular basis. The virus has the effect of transforming human males into Mimetic beasts; females are somehow immune, unless they naturally generate large amounts of male hormones. The virus is stimulated by human hormones, especially those released in great quantities during combat. During the second season, the pilots of Dannar Base struggle to balance the need to fight the Mimetic beasts with the danger of further infection. Eventually, it is discovered that Milla, who was trapped inside a Mimetic beast for five years, is the source of the vaccine humanity needs.

http://en.wikipedia.org/wiki/Godannar
This series is actually pretty good story-wise, it's exploration into relationships is good too.I'll give it an 8/10, but fair warning, it's pretty fanservice heavy(No nudity, but suggestive themes)I normally a fan of jelousy in anime since it adds to storyline but honestly it's gold here.
Watch full episodes here
http://www.animepile.net/search/Godannar----.html
or
http://www.animeshippuuden.com/category/godannar/

and download at www.animebreaker.com