Conversation so far:
What is meant by the UKJ character?
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.
What did the character represent?
he wanted to build up a bunch of other characters deriving from the other band's members or their friends.

Question: Who designed the character?
Self-contained rewrite: Who designed the UKJ character?