Unbeknownst to Jyaku and Megumi, in 1944, the Nazis attempted to summon the Overfiend's nemesis: the Lord of Chaos (Kyō-Ō). Top scientist Dr. Münchhausen and his son invented a perverse death-rape machine to summon the Lord of Chaos—but the machine overloaded; and helped to destroy half of Berlin—leaving Münchhausen II alive, but psychologically scarred.

During his adolescence, Münchhausen II discovers his father's journal and tries to uncover the secrets of the Jyujinkai and the Makai. He finally succeeds and reawakens Kohoki—a demon banished to hell for eternity—into the human realm and the two form an infamous partnership.

Cut to the present day and Münchhausen II is trying to fulfill his father's work—to summon the Lord of Chaos—but to make sure it will work this time, he needs a human sacrifice. And it just so happens Tatsuo's cousin Takeaki Kiryu is on the next plane to Osaka...