An earthquake transports Qin Yong and his classmates to Yuling Continent, a realm governed by spirit beasts. While his peers gain potent bloodlines, Qin Yong is reborn as the weakest spirit beast, a caterpillar (iron pupa). He obtains the "Devouring System," which enables him to evolve from prey to predator. Together with a school belle who became an empress, Qin Yong explores the continent, uncovering ancient secrets and a terrifying truth: the realm is a grand experiment of a divine conspiracy.