Iruma's life changes in a single act of mercy. Penniless and growing up in a harsh city slum, the kind boy hands his last loaf of bread to a badly hurt old man and cares for him until he recovers. The stranger turns out to be Don Sullivan, boss of the Babel Mafia, who later returns, takes Iruma away and pleads with him to become his grandson. Suddenly Iruma is heir to a huge gang of demonic mobsters, in a spinoff of the Iruma-kun series that mixes action with comedy.