The world is split between two factions: humans and monsters known as katawara. Although she is a katawara, Tama loves humans and swears to shield them from evil, even if that requires her to fight her own kind. Her brother Jinka, on the other hand, despises humans, despite being mostly human himself. The siblings are accompanied by a cowardly swordsman named Shinsuke, who seeks to learn how to become strong. Upon uncovering a plot to experiment on humans and transform them into monsters, the group vows to defeat whoever is behind it... Even if it means battling an entire army of warriors. The people they meet, the places they see, and the creatures they battle will be legendary!