=>REPOSTED FROM DA<=

"Once Upon a time, There was an Adventurer called Wolf girl. Despite having lots of energy and enthusiasm, she was the worst adventurer in the land. One day, she tried to fight the easiest enemy she could find to prove that she wasn't the worst - a Cat Slime. Unfortunately she tripped over the slime and fell into them, knocking both of them out in the process."

"When they woke up, they didn't have any memories, and didn't even realize they used to be two different creatures. They retained their slime insticts and biology, but were a lot kinder, energetic, and were slightly smarter. They called themselves Guu after a while, because they aren't the best at naming things."

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So this is Guu's origin story, I used the design for Non-stick Guu (for Wolf girl) along with the oldest version of her (for the Cat Slime) to try and explain why her appearance changed so rapidly.