Alchemists and onmyoji. Both have existed for millennia—mages who lend their services to the powers that be, and work on cases that cannot be solved by natural means. And on the Japanese Archipelago, their spheres overlap. While Japan has its traditional Bureau of Onmyo, Satsuma, a Catholic country formed out of the island of Kyushu, has an Alchemist Court, made up of families who have passed down the art of alchemy for centuries.
Noe Numasaki is an ordinary Satsuman high-school girl--ordinary, except for the fact that she’s haunted by the specter of a four-hundred-year-old swordmaster with a blade to grind. After a run-in with Justo Ijyuin, an alchemist who moonlights as a high-school delinquent, Noe gets caught up in the world of the Knights of the Monad, an alliance between Satsuma and Japan with the purpose of eliminating spiritual threats across the islands, and the many alchemists and onmyoji who maybe—just maybe—can help her with her possession problem.