The princess of the Vers Empire, Asseylum Vers Allusia, visited Earth as a goodwill ambassador, with Slaine Troyard, a boy born on Earth but raised on Mars, watching her depart. However, their procession was attacked by terrorists in Shinawara City. The Martian Knights on the front lines saw this as a declaration of war from Earth and descended from their orbital bases to launch attacks on various countries. Thus, the fires of war between Earth and Mars were reignited.