Blue Moon is one of the five major factions in the Advance Wars series. They initially appear in the first game as an antagonistic faction, opposing the heroic faction, Orange Star, but they are later revealed to have been manipulated into warring with the other factions by Black Hole and Clone Andy.
They were tricked into fighting the other nations by Clone Andy, who led an attack on them under the guise of the real Andy who worked for Orange Star. Blue Moon used this attack as an excuse to invade Orange Star and seize its territories. However, they were driven out by Orange Star forces under the command of the CO Andy were able to drive them out.
After it is revealed that all the nations were deceived by Black Hole, Blue Moon allies with the other forces to fight against it.
Blue Moon would go on to team up with the other forces again to fight Black Hole when it returned in Advance Wars 2: Black Hole Rising to try and conquer the Wars World again. In Advance Wars: Dual Strike, Blue Moon joins the other Wars World nations in forming the Allied Nations.
Advance Wars: Days of Ruin