Student Izumi Hoshino transforms into the special investigator Sailor Deka to hunt down vicious sex offenders. She guns down a despicable criminal responsible for driving her best friend to suicide, upholding justice. However, the criminals are resurrected as Onigansen by terrorist scientist Mr. Libreau, seeking revenge. Sailor Deka Izumi succumbs to their assault, suffering sexual violence at the hands of Mr. Libreau and the criminals, breaking both her mind and body. Ultimately, she meets a tragic bad end.