For my initial pitch I decided on developing a small story I found a few years back.
"The Cat and Rat: Legend of the Chinese Zodiac written by Ed Young"
Its a story about how the animals appear in what order in the Chinese Zodiac by taking part in a race and how the Cat does not appear in the Chinese Zodiac. The Rat tricks the Cat in order to win the race.
I heard the story a few years ago though an anime I watched. It told the story differently but still had the same principle of the Cat not being able to become part of the Zodiac.
There are many different versions of this story but I chose this version as it was an actual published book and had structure and gave the characters a small background and it was easily available to find online.