In a world engulfed by the enigmatic force known as "chaos energy," a deadly threat of monstrous entities called "Ghouls" infest the world. To combat this menace, a bureau known as the Extermination Bureau (EXB) is formed, comprised of the gifted individuals known as "Exterminators."

The story revolves around Shannon Hasewaga, a 22-year-old Exterminator that possesses a serious demeanor, driven solely by a desire to get the job done.