The human species escaped to space on the huge generation ship Sidonia after the Earth was devastated by enigmatic extraterrestrial lifeforms known as the Gauna. For the first time in a century, the Sidonia found itself under siege from Gauna after millennia of drifting across space. Faced with extinction once more, the Gauna were temporarily defeated owing to the human-Gauna hybrid Tsumugi Shiraui and ace Guardian mech pilot Nagate Tanikaze. After ten years... Sidonian citizens have a brief reprieve. Days pass in silence, and Tsumugi comes to recognize her affections for Nagate, who is now regarded as a Sidonian hero. Captain Kobayashi, on the other hand, has always understood that as long as the