"Gadget Trial" takes place in the future, decades after an unidentified world war, and focuses on the so-called "E-Series". This is a new generation of military equipment, representing a very advanced level of technology, developed by an organisation called "Eastern Treaty Union" (ETU) under the codename "Project 'Next E'". The E-Series units are human-like cyborgs or "bio-machines", constructed from various organic bio-alloys, and they are capable of regeneration and reproduction, similar to bacteria. Also, they can utilize "Reinforcement Units", special machinery which extends their capabilities beyond regular war machines. Furthermore, their artificial brain greatly surpasses human mental abilities, calculating complex mathematical problems in very short times, and deciding very quickly between various options on how to complete a certain task.