When Ayanami, The Empress, ascended into heaven, she left two children on earth, Sujin and Kogen, who both contributed with two objects, that together worked to protect men from the hellish creatures. The love that both of them felt for Empress Saimei raised jealousy and hatred between brothers. Therefore, Himukai kingdom was quickly divided in two, with two large families arising from both branches. The disputes ended up causing the first major war in Himukai.
Battles followed one another and Sujin quickly took advantage thanks to his heroes. At the end, Kogen forces fled by boat and eventually took refuge in the fortress of Kaidan over Yamanashi.
In this last battle Kogen was defeated and executed by orders of his own brother, along with all his officers and servants. The land was littered with corpses of men and animals, which were devoured by vultures and vermin. No one, since it occurred, dares to get close to that place, as they say that spirits roam at night and that the trees grow strangely in a land that is still painted red with the blood of the dead.
After this conflict ended, the Emperor started to declare as a traitor all those persons that dared to pronounce the name of his brother, his family or any person who accompanied him. He also ordered the destruction all images and documents that could prove in someway that his brother stepped on that land. So Kogen’s family was dragged by the wind, like autumn leaves, to a tragic end. So both Sujin and time took care of erasing all traces of their existence, and through centuries those ancient facts got forgotten, making the Kogen passage just a silent witness of what really happened.
But in the depths of the underworld, Kogen’s tortured soul demanded revenge, trying to escape the clutches of death to return to Himukai. There he made a pact with the gods of Yumi, agreeing that if they helped his revenge, he would then open the gates of heaven so they could cross back into its heavenly pastures. Thus a terrible night came, when the Empress Saimei found her death, and after this, the unexplained disappearance of Sujin. This chain of events were no accident and they paved the opportunity for centuries expected. So he, hungry for revenge, gathered his followers and returned to Himukai to bring death to all those who descended from Sujin; he would not spare the living, for they were already dead.