Sagi is a young man who is said to own a Guardian Spirit (one of many spirits which guides a person toward making wise decisions).
Sagi begins the game as a member of the Dark Service, an army which plans to kill the emperor, Olgan. He is reluctant to join them on their mission to kill the emperor, but does so because he desperately needs the money he is paid. When he, and the Dark Service members, reach the emperor's room, he finds the emperor already dead. However, Sagi is framed for the murder of the emperor, and is arrested. He is released by Verus, a government official, who, in return, asks him to perform missions.
Sagi, when knocked unconscious, is sent to a different world with different characters in his dreams. He knows little about his enigmatic past and in his adventures, he tries to learn more about it.