The stage is Beiron City, an independent city where special incidents called "D disasters" caused by "devils" occur frequently. In order to stop as many tragedies as possible, and to solve the curse of the devil that he himself suffered, the protagonist establishes a private military company (PMC) and confronts the "D disaster" with his friends.

The stage is Beiron City, an independent city where special incidents called "D disasters" caused by "devils" occur frequently. In order to stop as many tragedies as possible, and to solve the curse of the devil that he himself suffered, the protagonist establishes a private military company (PMC) and confronts the "D disaster" with his friends.