Crown Prince Sado
Apart from the fictional elements, a major focus is placed on two historical sources. The Memoirs of Lady Hyegyeong is extensively used during many flashback sequences relative to events that occurred before the death (1762) of Crown Prince Sado, while the official documents from the Joseon Royal Library are used for the current events: the "Wonhaeng Eulmyo Jeongni Uigwe" (Eulmyo=1795) for the procession itself, and the "Hwaseong Seongyeokuigwe" concerning the Hwaseong Fortress as a whole.