The fourth anime series in the Macross sci-fi mecha franchise, Macross Delta is set eight years after the events of Macross Frontier. In the year 2067 when humanity has spread across the galaxy, in the far-off Brisingr Globular Cluster, a strange affliction known as Vars Syndrome is causing people to lose their minds. To combat the spread of the Vars Syndrome, idol group Walkure, a tactical unit formed by five girls, uses music to neutralize the symptoms of those affected, while the Delta Squadron does battle against the Aerial Knights Valkyrie fighter team who are harnessing the infection to aid their war against the New United Government.