Klaus revealed in an earlier interview on TV that the character was a caricature of Whitfield Crane, info confirmed later by its author Moish Brenman (Whitfield's high school friend and Roger Lahr's roommate in their teenagehood). Moish became the genius painter for customisation skateboards and was involved in plenty of projects about Arts. He died during the Stairway to Hell sessions and was replaced by Daniel Mercer for the coverdesigns.  The UKJ he created is a boy showing a middle finger and hiding a bottle of beer behind his back, wearing a blue baseball hat, a dirty white T-shirt, green Bermuda shorts, white socks and Doc marten shoes ( or sometimes sneakers too). Moish was supposed to be the official and unique drawer of the band once they were signed by Mercury Records, but for still unexplained reasons he was replaced by Marc Goldstein (so damn cool and Goddamn Devil pictures).  Some unknown pictures from Brenman about UKJ are still in existence. In a conversation on the UKJ forum in 2006, he revealed he wanted to build up a bunch of other characters deriving from the other band's members or their friends by the time he was the official drawer but that project has never been broacasted.  Plenty of pictures of the UKJ are made for free for the UKJ fans. They are coverdesigns bootlegs to replace those which are disappointing (Goddamn Cool or As ugly as it gets for instance) or for old or new bootlegs without sleeves. The very great majority of those sleeves are made by UKJ Fan Artists or Mercer-Moish's fans such as Karaokeman (who is more a customizer of other artists work), Kiplegends (Iamthewolf), Marcos Moura, Vivien Hup for the most current. Those pictures are not for lucrative activities and made as a tribute to Brenman or Mercer or for fun for fans and a warning message is always put on every bootleg about the consequences if that rule of 'NOT FOR SALE' would not be respected.

Answer this question "Who designed the character?" by extracting the answer from the text above.
UKJ Fan Artists or Mercer-Moish's fans such as Karaokeman (