The Cuniculus of Paradise

In the near future, humanity has harnessed infinite energy called Akasha Particles, but this advancement unleashed giant beasts that reclaimed dominance over the ecosystem. Humanity's survival now rests on large humanoid weapons called Exos piloted by mercenaries. The protagonist is a former mercenary who lost the ability to use Akasha Particles in a past accident, rendering him unable to pilot an Exo and leading him to view himself as defective. Drifting aimlessly in a reclusive life, he encounters a young girl who dreams of becoming an Exo mechanic. She has inherited her late mother's designs and constructed an unconventional Exo that functions without relying on Akasha Particles—technology scorned as outdated by contemporary standards. When this defective mercenary and the pilot of this antique machine meet, their intertwined fates begin to unfold.