On one side, a boy who simply wishes to be with the girl he loves. On the other side, a madman who once tried to rule over the world. One chases after the future, while the other clings to the past. The stories of these two men intersects when they both found themselves forced to work together to survive the impending war. [Crossover between Gundam X, Gundam 00, and Gundam SEED]

The Dragon Witch and The Little Santa, both owes their existence to a certain Holy Maiden, while also representing a different aspect of that Holy Maiden. Now both of them suddenly finds themselves on a new land with their Master nowhere in sight, while a Great Holy Grail War looms on the horizon. What will their interference brings?