Includes Vol. 4-6 of the Fire Force manga. During his infiltration of Company 1, Shinra discovered that someone is using bugs to turn people into Infernals. He must identify the true culprit and separate friend from foe if Company 8 is to make any progress in their mission to uncover the truth of spontaneous human combustion. But complications arise when more hidden enemies come to light, and though the Fire Force should be united, each Company is pursuing their own agenda. Worse, the brother he thought long dead might be mixed up in it all somehow!