Thousands of years ago, on the Empty Century Continent created by God (also known as Land Alpha), there were two powerful empires of equal strength, namely the 'Alwieskotter' military empire with armed technology as its core and the 'Isbrook' sanctuary with theocratic spiritual power as its core. The story begins with the protagonist Hope's father, Ed Green, being rumored to have conspired with the military empire, betrayed the Sanctuary, and used the Key of Life (the Key of David) to open the door to the Doomsday Judgment, thus breaking the seven sealed Doomsday Seals one by one, marking the beginning of the 'Apocalypse War'. Seven years later, Hopgreen, who had made some achievements in the military academy, learned from the Empire King Richard that his father Edgreen was made a scapegoat because of a dispute between the top leaders of the Holy Domain. In order to pursue the truth seven years ago, Hopgreen returned to the place of the past with the hope of the king and the conspiracy of the empire (to break the barrier of the "Isbrook" sanctuary, the "Wall of Sighs").