In Taimei, the capital of Kouraikoku, a mysterious incident has occurred where strange fireballs—Onibi (demon fires)—are being sighted. Soon, rumors begin to spread among the people that this is Heaven's anger over the accession of the current Emperor, who has a mother of low Social Status. Taking the situation seriously, the Emperor ordered his close official, Tenyuu, to head to Toumei to find a capable Alchemist. There, Tenyuu encountered Reien, a girl Alchemist dressed as a boy. Having accepted Tenyuu's request, Reien ends up infiltrating the Inner Palace to unravel the Mystery of the Onibi using her knowledge of Alchemy...!? The Alchemy × Inner Palace Mystery begins!