A new television series has shed light on the bizarre Japanese trend for 'bagel heads'.
The extraordinary look, which is created by injecting saline into the forehead, then pressing in the centre of the swollen area with a thumb, is a hit on the country's underground body modification scene.
The dramatic results of the two-hour treatment last just 16-24 hours, after which the saline is absorbed by the body and the forehead reduces back to its normal size.
The process is revealed on National Geographic's Taboo, where three people are seen undergoing the treatment in Tokyo.
The trend was initially sparked by the artist Keroppy, according to an interview in Vice last year.
He told the magazine how he came across it in Toronto, Canada, at the extreme body modification convention Modcon in 1999.
'I happened to meet Jerome, who was the person who pioneered saline infusions,' he explained. 'We stayed in contact, then eventually I experienced saline with him in 2003 and he gave me permission to bring it to Japan.
'I set up a team in Tokyo to administer infusions for other people. That’s been going since 2007.'
He said fans of the procedure enjoy 'saline parties' about twice a year, though some people will take their 'bagel head' to clubs and fetish parties.
The saline injections can be done on any part of the body - some people have even had 'scrotal infusions', he revealed - but for the most part, it is just the forehead.
On its (thankfully) short-term effects, Keroppy joked: 'We enjoy being freaks for the night!'