Komada and Koshigaya are scientists - and Bio Hunters, agents who battle the Demon Virus that causes humans to mutate into weird monsters. Komada has contracted the virus, but something in his immune system enables him to control his transformations. When Komada rescues Sayaka Murakami, the granddaughter of a famed psychic, from a gang of thugs, he unwittingly pits the Bio Hunters against the powerful politician Seijuro Tabe, who is to be the next prime minister. They discover that Tabe is actually the horrible monster that's been roaming Tokyo, killing young women and eating their livers. He's no longer human, but a corpse possessed by the devil. The final battle pits Komada in his monster form against the tentacles and fanged jaws of the possessed Tabe, although it is Koshigaya who administers the coup de grace.