Eiri Shibamura serves as a mechanic within the 108th Guard Squad, a remote defense force stationed in Aomori. This unit, composed of inexperienced pilots and support personnel, defends against Phantom Beasts while struggling with inadequate resources and low military standing; it often functions as a reassignment post for underperforming personnel. Eiri Shibamura's duties focus specifically on maintaining and repairing the squad's mecha, the one-seater eikougou and two-seater koukigou models, both derived from earlier Type-99 shikongou HWT designs.