All states of the floating islands are forced to end their feuds and unite against a common threat from the west. A vast empire sends an expeditionary corps through the mountains to destroy first the Tethered Kingdom, and then all the other “heretics.” The united army holds out through the hardest battle, actively using every piece of newly accumulated weaponry. Defeating the enemy, the main hero confirms the rank of admiral he has been given and leads the best soldiers on a retaliatory raid. After the war is over, he returns home to found a school for air captains and begin a peaceful life.