In the world of Daikuuriku, everyone is born female, and chooses which sex they wish to become at age 17. In this world, the peaceful theocracy of Simulacrum is guarded by magical flying machines called "Simoun", which can only be piloted by young girls who haven't chosen a sex yet. The Simoun can activate a magical power known as "Ri Maajon" that can destroy large numbers of enemies at once. When the industrialized nation of Argentum decides that it needs to invade Simulacrum to acquire the secret of the Simoun, war breaks out, drawing the Simoun "Sibyllae" (priestesses who fly the Simoun) into a lopsided battle. Because the war is raging, the Sibyllae are granted an exemption from choosing a permanent sex for as long as they're willing to keep flying. Aaeru, a determined young Sibylla with a mysterious past, and Neviril, the leader of Chor Tempest, Simulacrum's most elite Simoun squadron, must lead their fellow priestesses through conflict both within their ranks and in the sky.
Episode 1
Tragedy strikes Chor Tempest in its first battle against the air fleet of the Argentum Archipelago, and two mysterious new Sibyllae join the choir.
Episode 2
Elly must choose whether to become male or female when she visits the Spring to choose her sex, and Aer tries to convince Neviril not to follow Elly into the Spring.
Episode 3
Aer tries to convince Neviril to rejoin Chor Tempest and pair with her, as Chor Tempest struggles with its morale after its recent losses.
Episode 4
Aer searches for a new pair in the face of Neviril's continuing refusal, and she and Rimone encounter the enemy up close.
Episode 5
Dominūra arrives to try to turn Chor Tempest around, starting with Limone. Limone has her first flight as an auriga and struggles with demons from her past.
Episode 6
As Neviril remains reclusive, Paraietta wrestles with her feelings for Neviril, and with Kaim's feelings for her.
Episode 7
Two new recruits shake up Chor Tempest as the Arcus Prima prepares to host a peace conference.
Episode 8
Chor Tempest plays host to a foreign priestess as Simulacrum tries to make peace with Plumbum. But just how similar are their religions?
Episode 9
After rescuing the Arcus Prima from a trap, Chor Tempest faces its greatest threat: disbandment.
Episode 10
Dominūra finds Chor Tempest a new home while Arcus Prima is in drydock. But what is she really up to?
Episode 11
Chor Tempest joins with an infantry unit to carry out an airmobile assault, and finds itself on the front lines of the ground war.
Episode 12
Alty and Kaim are forced to try to fly together, but the shadow of the past haunts the two of them.
Episode 13
Aer upsets Neviril when she asks to try the Emerald Ri Mājon with her.
Episode 14
Dominūra asks Wapōrif to dismantle a Simoun to find out how it works.
Episode 15
Chor Tempest sorties one by one to search for a shadowy enemy, as the consequences of recent events hit home emotionally for many of its members.
Episode 16
Rimone and Dominūra attempt the Emerald Ri Mājon as the Messis comes under heavy attack, and repairs to the Arcus Prima are completed.
Episode 17
When Headquarters suspects that the enemy may be stealing helical motors from Simulacrum's holiest shrine, Chor Tempest is sent to investigate. They make an extremely surprising discove
Episode 18
The funeral of a Simoun pilot brings high-ranking Simulacran officials aboard the Arcus Prima, and gives them an opportunity to try to micromanage Chor Tempest.
Episode 19
Chor Tempest searches for the Argentine base ship that Alty and Kaim found, but Aer and Yun are left behind.
Episode 20
After the death of another of their members, the remaining Sibyllae of Chor Tempest must somehow find the strength to keep fighting.
Episode 21
As the war turns disastrously against Simulacrum, the mystery of the Emerald Ri Mājon is revealed, and the religious authorities have a special request for Aer and Neviril.
Episode 22
Chor Tempest carries out a last-ditch defense of the Simulacran capital as the war comes to a conclusion.
Episode 23
Simulacrum and its opponents come to a peace treaty. The condition: Chor Tempest must be permanently disbanded. Meanwhile, Yun investigates the mystery of the Spring and Onasia.
Episode 24
The members of Chor Tempest are ordered to go to the Spring to choose their permanent sex. Yun makes a fateful choice.
Episode 25
After the rest of Chor Tempest goes to the Spring, Aer and Neviril must escape to attempt the Emerald Ri Mājon.
Episode 26
Years after the war, the former members of Chor Tempest reflect on their lives.
