Unfair the answer

After detective Natsumi Yukihira brings an end to the police hospital terrorist case Natsumi is transferred to the Nishimonbetsu Police Station in Hokkaido Meanwhile a series of grotesque murders occurs in downtown Tokyo involving nails placed in the body of the victims The fingerprint of Natsumis exhusband freelancer journalist Kazuo Sato is found on the the body of a victim and Kazuo is placed on the most wanted list Soon after Kazuo finds Natsumi and hands her a USB memory stick The device contains information on a secret organization within the police department Kazuo tells Natsumi that the series of murders are warnings and suspects become the next victims Natsumi is then arrested as a suspect Tokyo prosecutor Katsuaki Murakami appears at the Nishimonbetsu Police Station to investigate