Fortress of the Diety

While searching for his missing sister, Eiji Shigure secretly enters the castle of millionaire Klein Sandman. There he meets the castles strange inhabitants and is selected to join in Sandmans mission to stop a destructive alien known as the Zeravire. The teams weapon, a series of fighting robots designed by Sandman called the Gran Kaiser and the Gran Divas who when needed join together to form Gravion.