S1·E6 Sixth Skull

Natsuno investigates local stories of the "Risen" after seeing that someone had disturbed the torn-up pieces of Megumi's letter he threw out. Meanwhile, Masao's brother Hiromi has died of the same mysterious causes, and Masao is bedridden with peculiar bite wounds.

Seishin meets with Dr. Ozaki with his findings, but Dr. Ozaki yells at him over his own frustration with not being to help his patients. Later, Dr. Ozaki notices that most patients with symptoms of the epidemic have "insect bite wounds" on them, and has some success when he performs a blood transfusion on Gyouda Etsuko and she is able to return home. However she later dies after she does not report to the clinic for a follow-up.

Natsuno asks Dr. Ozaki if there was any possibility that Megumi might not have been dead, to which Dr. Ozaki responds jokingly that she would be a zombie or a vampire. This starts Dr. Ozaki thinking that maybe this isn't an epidemic...