A Norwegian who called himself 'The Eunuch Maker' has admitted to performing castrations and broadcasting the footage live to a paying audience for six years.
Marius Gustavson, 46, performed extreme body modifications, including the removal of penises and testicles.
The operations were filmed and uploaded to Gustavson's 'Eunuch Maker' website, where subscribers had to pay to watch them.
He earned £200,000 over six years.
The practice is linked to a subculture in which men become 'nullos', short for genital destruction, by having their penis and testicles removed.
Marius Gustavson, 46, (pictured) performed extreme body modifications, including the removal of penises and testicles.
Former nurse Nathaniel Arnold, 46, (pictured) removed Gustavson's body parts and will be sentenced on January 12
Jacob Crimi-Appleby, 23, (pictured) froze Gustavson's leg requiring amputation and admitted deliberately causing GBH
The group was probably inspired by the asexual Japanese illustrator Mao Sugiyama
The sick plan included no fewer than 29 extreme body modifications, the removal of body parts and the trading of body parts with eight other men.
Gustavson is now wheelchair-bound after his leg was frozen and then amputated. His penis and nipple have also been removed.
He appeared at the Old Bailey today via video link from HMP Belmarsh and admitted three further counts of causing grievous bodily harm with intent.
Gustavson previously admitted conspiracy to commit grievous bodily harm, two counts of causing grievous bodily harm with intent and one count of possessing criminal property, namely money.
He also admits making and distributing two indecent videos of a child between January 2017 and January 2020.
David Carruthers, 60, who previously worked as a surgical assistant, and Janus Atkin, 37, from South Wales, also appeared in court today.
They deny conspiracy to commit grievous bodily harm.
A trial date has been set for March 4, 2024.
Romanian Ion Ciucur, 28, who works at a hotel in Gretna Green, Scotland, has admitted conspiracy to cause grievous bodily harm by taking part in castration by restraint and other modification.
It is said that he was “part of Gustavson's inner circle.”
German Stefan Scharf, 61, is charged with conspiracy to cause grievous bodily harm.
He is accused of taking part in one procedure involving the removal of a testicle at an apartment in Camden, London, in July 2019.
He will enter a plea on January 12.
Former nurse Nathaniel Arnold, 46, Jacob Crimi-Appleby, 23, and Damien Brynes, 36, removed Gustavson's body parts and will be sentenced on January 12.
Arnold, Crimi-Appleby and Brynes admitted causing grievous bodily harm with intent.
Crimi-Appleby froze Gustavson's leg, requiring amputation. Brynes removed his penis while Arnold was involved in the partial removal of his nipple.
Arnold also admitted stealing lidocaine while working as a nurse at Chelsea and Westminster Hospital between January 2016 and January 2022, and possessing extreme pornographic images.
Gustavson's alleged 'right hand' surgeon Peter Wates, 66, has admitted conspiracy to commit grievous bodily harm.
As a surgeon, he would play a major role in a large number of procedures.
Japanese artist Mao Sugiyama became a famous 'nullo' in 2012 after his genitals were removed, frozen and then boiled and served at a banquet
Diners at the exclusive banquet in Tokyo were given Sugiyama's boiled genitals or beef or crocodile meat
Carruthers' partner Ashley Williams, 31, admitted causing grievous bodily harm with intent to Atkin at his home in Newport, South Wales, on November 7, 2017.
Gustavson, Scharf and Ciucur are taken into custody, while the others are on conditional bail, which includes a curfew and residency permit.
Crimi-Appleby, from Epsom, Surrey, Arnold, from South Kensington, and Byrnes, from Tottenham, admitted causing GBH with intent.
Scharf, who has no fixed address, is charged with conspiracy to cause GBH with intent.
There are an estimated 10,000 to 15,000 volunteer 'Nullos' worldwide, although the actual number is unknown.
Astonishingly, two-thirds never tell anyone they don't have genitals, including their families, according to a 2014 academic study.
Many of the “cutters” – jargon for those who perform the procedure – have a medical background. Those who have had their genitals removed also claim that veterinarians have been known to do this.
A man named William previously told the Daily Beast that he decided to spend the money to do it in a hospital.
He said: 'The risk of something going wrong is extremely high.
“I also don't want to look like Frankenstein at the end of the procedure.”
A castrated minister named Benedictus said, “It is not nearly as strange and difficult to try to become a eunuch now as it was thirty years ago.
'Now we have doctors who don't even blink an eye when you say you just want to remove your testicles, or just add a vagina. I never saw this coming.”
The most famous modern 'Nullo' is Japanese artist Mao Sugiyama, who had his penis and testicles surgically removed by a doctor in March 2012 before charging guests. His nipples have also been removed.
They were declared free of infection and were frozen for two months before being served at a banquet in Suginami, a residential area in western Tokyo.
After initially offering to cook his penis for a single guest for £800, he ended up charging five guests £160 each to eat the meal, which was garnished with mushrooms and parsley. Police charged him with indecent exposure.
Sugiyama, who goes by the nickname HC, said he had initially considered eating his own penis, but decided to serve it up instead.
He cooked the genitals, which were removed in early April 2012, shortly after his 22nd birthday, himself under the supervision of a chef.
Sugiyama donned a traditional chef's outfit before carefully seasoning and burning the genitals on a portable gas cartridge burner.
Guests had to sign a waiver so he couldn't be held responsible if they got sick.
Sugiyama's first message on Twitter read: 'I'm offering my male genitals (full penis, testicles, scrotum) as a meal for 100,000 yen (£800). I am Japanese.
'At the age of 22, the organs were surgically removed. I was tested for venereal diseases. The organs functioned normally. I did not receive treatment with female hormones.
'The first interested buyer will get them, or I will also consider selling to a group. Prepares and cooks as the buyer requests, at the location of his choice.
'If you have any questions, please contact me via DM or email.'
In total, about 70 people attended the event in Tokyo's Suginami district. While five people hid in Mao Sugiyama's genitals, the rest ate beef or crocodile.
It was reported that the five people who ate the unusual showpiece dish were a married couple, a manga artist, a 32-year-old woman and a 22-year-old event planner.