Directly following the conclusion of Urotsukidoji 3, 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.