Ernst opens the Gehenna Gate so he can destroy Gehenna. When Yukio's blood mixes with that of Rin, it awakens his demonic powers. Satan shows Yuri's past to Yukio. She was an Exorcist who let him possess her so he could experience Assiah, the human world, as a human, and became pregnant with the twins. Enraged, Ernst ordered her dead. Satan unintentionally caused the Blue Night to free Yuri, who gave birth before dying. Mephisto and Shiro were sent to kill her children, but Shiro was unable to do it, adopting them instead. In the present, Satan possesses Yukio.