Simoun

In the world of Daikuuriku, all people are born female and must decide whether to remain women or become men when they turn seventeen. The theocracy of Simulacrum, a peaceful nation, is protected by magical flying machines called "Simoun," which can only be piloted by girls who have yet to choose their sex. These Simoun wield a devastating power called "Ri Maajon," capable of wiping out entire enemy forces at once. When the industrialized nation of Argentum invades Simulacrum to seize the secrets of the Simoun, war erupts, forcing the priestesses known as "Sibyllae"-the pilots of the Simoun-into an uneven fight. With the war raging, the Sibyllae are allowed to delay their choice of permanent sex as long as they continue flying. Aaeru, a driven young Sibylla with a hidden past, and Neviril, the leader of Chor Tempest-Simulacrum's most skilled Simoun squadron-must guide their fellow priestesses through struggles both among themselves and in the skies above.