Nightmare Detective (悪夢探偵, Akumu Tantei) is a 2006 Japanese horror film directed by Shinya Tsukamoto and released by Movie-Eye Entertainment Inc, starring Ryuhei Matsuda and Hitomi.

As he leaves, Kagenuma telepathically hears the selfish thoughts of Mitake's children, and realises that a messy legal battle is about to commence.

Her own prickly personality does not help matters; she interprets their casualness at crime scenes as a lack of professionalism.

Her first case is a young woman who has been found dead in her apartment, horribly slashed with a blade placed in her own hand.

The fact that the apartment was locked from the inside convinces Ishida and Wakamiya that the case is a suicide; Kirishima is not so sure, as no note was left and a neighbour heard the victim crying out for help.

Kirishima discovers a link between the two unrelated victims; both had last dialled the same number, a sequence not registered anywhere in the country.

O reveals that he originally wanted to die alongside the first victim, but instead somehow crawled into her mind, feeling a rush and hunger to kill her.

In the dream, Kirishima is chased around a derelict school, ultimately being confronted by her inner self, who berates her for her weakness.

Kagenuma unlocks a repressed memory of O, revealing that, as a child, his teacher locked him in the same furnace Kirishima is in, alongside his sister who is killed when trying to escape.