Mother Tamaki and daughter Yumi begin a new life in their respective remarried families. A four-person household forms with a strict yet kind father holding the family together, and a brother suffering from illness. From the moment he first sees Tamaki, the brother fixates on her not as a mother figure but as an object of desire. As warmth and darkness intertwine within the household, a story of forbidden lust, lingerie, and incestuous tension unfolds between the big-ass milf stepmother and her obsessed stepson, blurring the lines between family bonds and carnal urges.