The setting is Paris. Regis and Yuui, who as children became stepbrothers due to their parents remarrying, are dancers in a top ballet troupe. Losing both mother and father, with just the two of them spending each day together, it wasn't long before it reached the point where, late at night, elder brother Regis and the captivating younger brother Yuui weave a glorious and indecent stepbrother romance.