Nishikawa Kenji has made it his life's work to defeat the massive beasts that emerge from the unexplored depths of the Abyssal Forests. His existence is a simple one, living day to day and never worrying too much about what the future holds. However, Kenji's comfortable simplicity is shattered when he encounters a strange boy in an abandoned library, and soon he realizes that there is far more to the mystery of the Forests than he'd ever realized before.