The story is set in a not too distant future, in which Earth has been overrun by a horrifying technovirus. Mechanical parasites, mistakenly created in an attempt to advance technology, attach themselves to human spinal cords and turn their hosts into cyborgs, called GM. The Original GM were created by Gaia, a program designed by humans to regulate nature. Gaia malfunctioned and started creating their own GM. Currently, Gaia is repairing parts of it that were damaged, and once this is done, it will attempt to destroy the Earth.
Desperate to rid themselves of this technological terror, the remaining human survivors try to band together and learn to defend themselves against these android enemies.
Carol is an artificial being that was created specifically to save mankind. Unfortunately, in her youth she suffered greatly at the hands of the very humans she sought to save, and lost sight of her mission. Only through the kindness of one human girl named Shiori was Carol able to find her focus and a reason to save the world; for Shiori's sake.
The two reunite years later, as Carol saves Shiori from her friend Elena, who was tragically infected with the parasitic virus. Although Shiori doesn't remember Carol at first, Carol remembers Shiori and stops at nothing to protect her and express her love for her. Though Shiori is uncomfortable and embarrassed with Carol at first, she quickly grows to return her feelings. However, the two soon find out that their deep love isn't just a small matter between the two of them; it'll be a big factor in saving the entire world.
