In the near future, an ominous red star suddenly appears in the sky. Its presence is about to bring about the extinction of all life on Earth. The unified government proposes an evacuation project to take all of mankind into space, but in order to make the seemingly impossible project a reality, 'felixes' are brought into the world. Engineered to be highly intelligent with perpetual youth and longevity, the genetically modified superhuman felixes stand as humanity's only hope for survival.

Sion, the most gifted of the felixes, has been kept in a research facility built on a solitary island for the past hundred years. Her sole purpose, saving all of humanity. Ryou Haruna, a soldier from the Earth's unified government is sent to watch over Sion, who desperately seeks freedom from the military that's imprisoning her. Earth's last love story is about to begin.