The world is sharply divided between two factions: humans and katawara, monstrous beings. Tama, a katawara, harbors a deep love for humans and is determined to safeguard them from malevolence, even if it requires confronting her own kind. Conversely, her brother Jinka, despite being mostly human, holds a strong disdain for humanity. The siblings are joined by Shinsuke, a timid swordsman aspiring to attain strength.
As the trio stumbles upon a sinister plot involving the transformation of humans into monsters through experimentation, they pledge to thwart the perpetrators, even if it entails facing an entire army of formidable warriors. The encounters with diverse individuals, the exploration of various places, and the battles against extraordinary creatures promise to carve out a legendary tale.