Romance battles against armed robot soldier's misadventures in everyday life, attention to detail technology. The leading role is played by "black technologies" and the mystery of their appearance. The main strike force there are fighting robots or Arm Slaves.
Unbeknownst even to herself, Kaname possesses special knowledge that numerous organizations would like dearly to control for their own means. As such, Sōsuke is assigned to infiltrate her high school in order to protect her while pretending to be an ordinary student, and without her knowing that she's in danger. Sōsuke, unfortunately, has no social experience outside his military life, having been literally raised as a soldier, and thus has no idea how to properly act in civilian life.