A brave knight named Oersted, a hero beloved by the people, defeats his best friend, the wizard Straybow, in the final round of a fighting tournament, winning the right to marry Princess Alicia of Lucretia. That night, she is kidnapped by the Demon King. The next day, Oersted and Straybow set out to rescue her. First, they find the heroes who defeated the Demon King thirty years prior, the knight Hash and the priest Uranus, and convince them to join. They fight and defeat the Demon King, but Hash dies due to the plague, Alicia is nowhere to be found, and Straybow is seemingly killed by falling rocks. Oersted and Uran*s return to Lucretia in defeat. That night, Oersted is tricked into slaying the King of Lucretia by an apparition of the Demon King after seeing what looks like Straybow exit his room. He is accused of being the Demon King himself, and he is later imprisoned. Uranus, who is also a prisoner for being a "demon ally", uses the last of his strength to help him escape. Oersted returns to the mountain of the Demon King and finds Straybow alive, having faked his own death. Straybow reveals that, out of jealousy for Oersted, he sold his soul to become the next Demon King, and tricked Oersted into killing the King. Oersted is forced to kill him. He then rescues Alicia, but she confesses her love for Straybow and blames Oersted's heroism for Straybow's fall to evil, she then kills herself. Oersted, in his grief, searches through his memories and realizes that he no longer has anything to believe in, anyone to love, and that he has nowhere to go. Oersted snaps, sacrifices his soul to become the next Demon King, and names himself Odio, deciding to teach humans "the folly of their selfishness". He then takes revenge on all of Lucretia, killing everyone.