Guinea Pig: Mermaid in a Manhole

Guinea Pig: Mermaid in a Manhole (ギニーピッグ マンホールの中の人魚, Ginî piggu: Manhôru no naka no ningyo) is 1988 Japanese body horror movie featuring a mermaid portrayed by actress Mari Somei.

Plot
An artist whose wife has left him, still paints most of his time. He ventures into the severs to gather inspiration on macabre images.

The artist finds a mermaid in a sewer and recognizes her from before. The mermaid was trapped in the sewers after the river disappeared. The artist decides to draw her from now on. Once he notices that the mermaid is hurt he takes her home with him, and puts her in a bathtub. He tries to help her, giving her medicine. The mermaid reminds him that he should draw her, as that was his mission. The artist starts drawing her again, but stops when she gets worse, and decides to take care of her, cleaning her and giving her fresh fish for food. The mermaid gets gradually worse and worse and her body is slowly taken over by boils. The mermaid reveals that her body contains seven colors inside her, and she wants the artist to cut her boils and collect the colors, as she knows she has little time left. Once he had all the colors, the artist resumed the painting, trying to match the ever changing looks of the mermaid. Mermaids condition worsens, and worms start crawling out of the boils, The painter thinking she died resumes the painting, a behaving erratically. The mermaid recovers for a moment, but still wants the artist to paint her. The artist finishes the painting, and promises to look after her now, but the mermaid asks him to kill her.

The artist looses his last sanity in the process, and chops up the body, curiously the body part look healthy and human.

The neighbors notice blood dripping from their ceiling and go to investigate, they find the artist completely lost sitting amongst the body parts still hacking at them. They call the police, and the artist is taken to the insane asylum. His wife had a stomach cancer in the last stages and had been bed ridden for along time. Everyone thinks it was his wife he killed, and the autopsy confirms it.

Links

 * Guinea Pig: Mermaid in a Manhole page on IMDB