The title involves twin sisters, Amatsu Ai (天津亜衣) and Amatsu Mai (天津麻衣), who become virgin priestesses that must watch over the boy, Onimaru (鬼麿), a distant relative of theirs. It becomes his choice to make the world a hellhole of debauchery or keeping as it is. Onimaru (鬼麿) is the descendant of a line of men, of whom the founder was betrayed by the Japanese government, and whose spirit wants revenge through his descendant, by making Onimaru a sex depraved demon king. The founder is the younger brother to two twin sisters. The three of them are the result of a union between a fisherman and an Angel (Tennyo) of the Buddhist tradition.