An anime only character; Following the footsteps of his father who died in the service of Adolf Hitler, he is the son of a mad Nazi German scientist, hell bent on resurrecting the Kyō-Ō and dominating the world.

Twenty-five years ago, the world was annihilated. With the coming of the Overfiend, God of all Gods, the human, demon, and beast realms collapsed together in chaos. With the promise that he would be born in 100 years to re-create his failed world, the Overfiend settled back to sleep within his mother's womb. 
But something has gone terribly wrong... 
Now the Overfiend is born prematurely and awaits the coming of his natural the enemy, the Lord of Chaos. His only hope for survival are Amano Jyaku and his sister Megumi. But destiny has moved in ways that even the Overfiend could never predict, as a new race of half-breed demon beasts has evolved. 
As Amano travels to the kingdom of Azuma to investigate the appearance of the Lord of Chaos, he is swept up in the world-conquering schemes of Caesar, Azuma's dictator. 
Against the backdrop of a demon beast slave revolt and the return of the diabolical Munhihausen, only Amano and the demon beast Buju can save the world from another fiery destruction. With the fate of the earth and its inhabitants hanging in the balance, all wait to see what the coming of the Lord of Chaos will bring...

Directly following the conclusion of Urotsukidoji III, the survivors of the Azuma kingdom genocide travel aboard a futuristic tank with Osaka as the destination. There, they plan to face both the Overfiend and their own fates as well. Along they way, the stumble upon a civilization beyond imagination, where children cruely rule over the adults. It is up to Amano Jyaku to save his friends from this sinister land and its evil ruler, Ellis. Shortly after their encounter, Sui Kaka Ju's sister Yoenhime summons Munhihausen, who transforms her into the menacing Yoenki. At last, she is strong enough to reap revenge on Amano for killing her brother. But Munhihausen has his own hidden agendas. The Urotsukidoji legend will finally reach its climax in Osaka, when Kiojo, the sweet and innocent Himi, and the Chojin meet face to face. 

Nazi Germany - 1944: As American bombers soar towards Berlin, a revolting Satanic rite takes place below - Hitler and his minions are using the monstrous Nazi Death Rape Machine to render the dimensional boundaries separating the Human World from the World of Man-Beasts and the World of Monster Demons. Dr. Munhihausen Sr.`s life work is about to come to fruition - the conjuring of the Overfiend! 
Cut to modern day Tokyo - Munhihausen Jr. searches for a monster with strength enough to conquer the omnipotent Overfiend. Since legend says that he who kills the Overfiend will rule all three worlds forever, Munhihausen is determined to slay the Overfiend and assume complete control over all three dimensions. His efforts seem fruitless - until Nagumo`s cousin Takeaki, infused with Nagumo`s blood after an accident, begins to develop monstrous powers. 
As Man-Beast Amano Jyaku and his sister Megumi, together with faithful accomplice Kuroko attempt to thwart Munhihausen`s evil plan, nothing seems likely to prevent Munhihausen, descendant of a race of brutal tyrants, from enslaving the world under his despicable rule!

[Website](https://demon-kakka.jp/index.php)

Demon is an Akuma (an evil kind of kami) masquerading in the human realm. He is the former vice-king of Jigoku (Hell) and the founder of Akumakyou (a demoniac religion).  Kogure preached his "religion" as the leader of [Seikima-II](https://anilist.co/staff/202525/), a religious group whose aim is to conquer the earth via heavy metal music. In mid-2009 he changed his persona to Demon Kakka ("His Excellency Demon").

(Source: Wikipedia)

During World War 2, the Nazis attempted to breach the barriers between the three worlds. They failed then, but a Dr. Myunihausen (Munchausen?) tries again, through the manipulation of Nagumo's brother Takeaki. His goal? To have the Chojin replaced. 
As Takeaki is injured in the approaching flight, Nagumo donates some of his blood to save his life, thus infusing Takeaki with the powers of the overfiend. And the results might be too much for Tokyo, perhaps even the overfiend himself, to bear. 
(Source: themanime.org)

Münchhausen II