Rin, a dark-skinned peasant girl in the Nikara Empire, passes a nearly impossible test and is allowed into an elite military school where she discovers a deadly aptitude for the ancient art of shamanism and a bond to the god Phoenix. She develops her gift with the help of her insane teacher and psychoactive substances. The Federation of Mugen, who used to occupy the Nikara Empire after the First Poppy War, and nearly won the Second Poppy War, is close to starting a Third Poppy War and Rin's power is the one thing that could win that war--but could also destroy all of humanity.