Erin is a young girl who lives with her mother in a village which raises war-lizards, called Touda. We see her daily life, which changes as she grows up. Meanwhile, there is growing tension between the two provinces of the country she lives in.

Kemono no Souja was first published in 4 tankoubon from November 21, 2006 to August 11, 2009. It was later republished in 8 volumes under the Aoi Tori Bunko label. The first 2 tankoubon novels were published in Swedish as Besttjusaren by Ordbilder from December 18, 2009 to June 9, 2011. The novel was published in English in two books titled The Beast Player and The Beast Warrior by Pushkin Press from February 21, 2018 to July 30, 2020, and by Henry Holt and Co. from March 26, 2019 to July 28, 2020.