From ANN:

In the year 2104, lots of local armed conflicts threaten the world peace. Soon, however, a new force appears: Dancouga, a gigantic super robot or uncertain origin. It appears out of nowhere and always aids the losing side. Its true objectives are unknown. At some point, four absolutely unrelated people, Aoi Hidaka, Kurara Tachibana, Sakuya Kamon, and Johnny Burnette, are invited by an organization that claims to be behind Dancouga… as its pilots. From there on, their search for the truth behind Dancouga’s mission and the battle to end all wars begin.