Ryoichi 'Keroppy' Maeda helps the "freaks for the night" of Tokyo get into character by dripping saline into their foreheads for two hours while they depress the center of the swelling, creating the signature "bagelhead" look:
Two hours! Fucking hell. How long does it last?
Just one night. The body absorbs it over time so by the next morning it just goes back to normal. We enjoy being freaks for the night, ha ha.
Does the skin ever start to sag?
No. Everyone I know who has done it, no matter how many times, their skin has gone back to exactly how it was before.