High school student Kazuki Muto has a dream about how he was killed in a fight with the monster, protecting a mysterious stranger.Soon the dream starts to come true: he and his sister attacked by a monster, like a huge snake. Tsumura Tokiko, the girl from his dream, telling him that this monster called the homunculus and that his death was not a dream. However, the girl revived Kazuki via kakugana.Tokiko explains that kakugan - this alchemical deviceable to give strength to fight homunculi. With kakugana Kazuki creates itself alchemical weapon in the form of a huge lance. Along with Tokiko and Kazuki its alchemical weapon fighting the homunculi and their creator.