[2] 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.

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.

Thus the military executive staff decides to have field trials, to test which design is better in battle, prior to a pending mass-production.

She has very limited offensive and defensive force, but she is the only unit capable of infiltrating an enemy building, turning it over to the player's side.

Izen is the archetypal "sunny idiot" or genki girl of the team; thinking positively, acting cheerful and making silly comments.

She is overly confident with her superiority compared to ground forces, which fuels Yu-ri's and Hisoka's constant teasing, stating that she is a perfect killing machine with her ranged, emotionless, shoot-and-forget attacks, thus making her feel very awkward.

Sōka can be compared to the stereotypical ōjo (high self-esteemed, selfish, arrogant, princess-like) characters in anime and manga.

Voiced by: Ryōko Shintani Yu-ri is the automated artillery and anti-airforce (AA) rocket and missile launcher unit.

On July 21, 2006 Five Records released a collection of the songs and background music pieces, titled Gadget Trial Perfect Audiotracks.