the setting resembles a medieval europe judging by the architecture, the way people are dressed, and the local environment shown in the background. the world in which the story takes place is like an alternate universe in which, chronologically, many things do not makes sense. in fact, despite the medieval feeling with demons and magic, there are also technologically super advanced flying battleships and carriers, tanks and cities made completely of metal platings with siege machines. also, the pieces played by hamel and raiel on their instruments are actually real pieces composed by real historical composers such as beethoven, tchaikovsky, schumann, schubert, mozart, haydn, etc. despite many of these figures existing much later in history.