'Oh sweet bagels ... I look delicious'
Japanese body art has been taken to a whole new extreme with the emergence of the "bagel head".
The bizarre new trend is created by injecting saline into the forehead until it swells up, then pressing the centre of the swollen area with a thumb giving it a bagel-like hole.
Body art fans bored with piercings and tattoos are then left with a large swelling resembling the doughnut-shaped bread on their head.
The process takes two hours to complete, but results last for just 16-24 hours as the body absorbs the saline and the forehead returns to its normal size.
A clip from the National Geographic programme, Taboo, shows three body art enthusiasts attached to saline drips inserted into their foreheads.
One customer said he felt a "relaxing sensation" as his forehead started to swell.
After his "bagel head" transformation was complete the man smiled and said: "Oh sweet buttery bagels ... I look delicious."
The man responsible for bringing the look to Japan, photographer and journalist Ryoichi "Keroppy" Maeda, told Vice magazine he had come across it at an extreme body modification convention in Canada.
"I happened to meet Jerome, who was the person who pioneered saline infusions.
"I experienced saline with him in 2003 and he gave me permission to bring it to Japan, so I set up a team in Tokyo to administer infusions for other people."
Keroppy said fans of the infusions attend "saline parties" held twice a year, and others wear their "bagel head" to clubs and fetish parties.
Saline injections could be performed on any part of the body, he said.
"You can inject it anywhere you want ... sometimes we do scrotal infusions as well."
But Keroppy said "bagel heads" were not the most extreme trend in the Japanese body art scene.
"There are practices that are far more extreme, for example, ear pointing, navel removal, amputation, Japanese traditional body suit tattoos."