In the near future, humanity has achieved remarkable progress with the discovery of infinite energy called "Akasha Particles." However, this advancement also brought about the emergence of "Gigantic Beasts," which dethroned humans from the top of the ecological hierarchy. The survival of the displaced humans now depends on large humanoid weapons called "Exos" and the "Mercenaries" who pilot them.
The protagonist, a former mercenary, lost the ability to use Akasha Particles due to a past accident. Unable to pilot an Exo, he considers himself a "defective" and wanders aimlessly, leading a reclusive life.
One day, he meets a young girl aspiring to be an Exo mechanic. She inherited her late mother's designs and built an Exo that is scorned as an "antique" by others because it doesn't use Akasha Particles, a stark contrast to the technology of their time.
A defective mercenary who can't use particles a...
