Theodore Morgan is merely a middle schooler who wants to have a normal high school life. Unfortunately, his life took a tragic turn when a madman burned down his hometown, leaving him and his sister traumatized.

Following the event, Theo met Louis, a red-haired teen who claimed to be the leader of the Leonia Academy Security Division's secret agency. Theo demonstrated potential, and Louis wanted to hire him for his secret squad.

Theo, who wanted to get stronger, agreed. However, he had no idea the depth of the horror that afflicted his whole country.