A young couple Aki and Kazuo are snatched off the street while having their first date as a romantic couple after a few years working in the same office, and wake up shackled in a basement, which has all its walls covered with plastic. With no further explanation, a sadistic madman degrades, tortures and mutilates them. Initially, he punctures Kazuo's belly with a screwdriver and slices his tongue, then rapes both, one at a time, forcing the other to watch. Sometimes he stops the torture to provide medical assistance and cure the couple's wounds, so they can continue alive for a long period of time. This way he cuts off all their fingers, makes collars with them, pops out Kazuo's right eye, removes the girl's nipples and cuts off her right arm. As the torture progresses, it is revealed he is simply doing it for sexual stimulation, and tells the couple he wants the two to survive. He finally castrates Kazuo, claiming he has found all the sexual relief he needs, so no longer needs the couple's "services". Then the couple is moved to a room which resembles a modern and clean hospital room, where the kidnapper takes care of the couple's wounds. While it is never explicitly mentioned on the movie, it becomes gradually apparent that the man has professional medical training, refined manners, taste for classical music and good wines and dressed with expensive clothes when he is not in surgeon dress torturing the couple. At some point he even mentions he is a wealthy man, which suggests he may be a reputable surgeon, not merely a violent sadist, looking for an extreme and different way to obtain satisfaction on his lonely life; however, the couple also notes the doctor has a particular rotting smell always present behind his clean and elegant appearance. After several days healing, the "doctor" simply tells the couple they will be free to go, he will turn himself to authorities and, as apology for all the suffering he inflicted to the couple, he will give them all his fortune which seems to be very large, as compensation. After all the horror, in a moment alone in the hospital room, Aki and Kazuo promises to support each other once they leave the place and become a formal couple. It is unclear if the madman changed his mind, or if playing with the couple's hopes to survive and being released soon was part of his mischievous plan from the beginning, but immediately after communicating to them they will be released, the next scene takes back the couple to the scary basement. After being drugged, they are shackled again, exactly as they were the first time. The "doctor" announces they must participate in one final test of love strength. He pulls out an extreme of Kazuo's intestines and attaches them to a hook. If Kazuo is able to cross the room to the other side (pulling off his entire intestines out of his body in the process), take a scissors and cut Aki's ropes to release her, both will be finally free. However, Kazuo fails due to blood loss and falls to the ground, agonizing (it is also revealed that the ropes restraining Aki have a metal wire running through them, rendering them impossible to cut with scissors; the task was therefore impossible). Aki begins to insult the doctor, telling him he is just the son of a whore that nobody cares about, and insists despite his refined manners and expensive clothes, he has an unusual and unbearable skunk odor, no matter how hard the tries to cover the stench. Angered, the doctor cuts off Aki's head in response and as her head falls down, it lands on the man's neck and bites him with her final breath. Kazuo on the floor, not dead yet, stabs him in the foot with the scissors as a supreme last action. The couple then dies facing each other. In the epilogue of the film, the madman is revealed to have survived what happened to him in the basement, although he cannot walk properly. He is in a quiet forest where he respectfully buries the couple next to each other in a traditional Japanese way, leaving the scissors on their tombs as a symbol. The next scene shows him back in the same car he used to kidnap the couple, covering himself with lots of perfume to hide his skunk stench while a girl is walking by, and the screen cuts to black as he goes after his next victim.