Outer space, the far future. A lone seed ship, the Sidonia, plies the void, ten centuries since the obliteration of the solar system. The massive, nearly indestructible, yet barely sentient alien life forms ...

Shou, the older brother, and Saya, the little sister, only have each other. The two of them lived happily, enjoying their peaceful lives together. That is, until Saya was bitten. When bitten by a pure-blood...