Beast Complex (found "Beastars" predecessor comic; 2013)
Beast Complex (sometimes called Original Beast Complex) was a self-published manga by the creator of Beastars, Paru Itagaki. (This Beast Complex is not to be confused with a manga of the same name published in 2016) Many similarities make it a predecessor/prototype of Beastars of some sort.
She created and released the comic while she was in college in 2013 and these Dōjinshi were sold independently at her college's art festival. There were three volumes released with three chapters in each volume. These comics focused on many characters seen in Beastars, but the world and characters are noticeably different from the canon of her now famous manga.
In 2020, the first two volumes were found and subsequently scanned and uploaded in the r/Beastars Discord. Later in January 2021, Volume Three was purchased by Youdoing, a member of the r/Beastars discord, and is currently in the process of being translated, along with volumes one and two.