To fulfill the forbidden desire hidden between close relatives, Takagi Takeshi devises a plan. After hearing his brother's wish to "have sex with my sister," he begins plotting to make it a reality. Staff members, disguised as gravure photographers, accompany the sister—active as an underground idol—to a hotel through the brother's introduction. As they prepare for the shoot, the brother suddenly leaves his seat. Seizing the opportunity, the staff begin instructing her on how to exude sex appeal and start touching her body. With her guard down, they stimulate her desires until she reaches climax. Then, with the sister blindfolded, the brother enters. The forbidden act succeeds as she surrenders to pleasure, moaning continuously while the brother penetrates her. The taboo of incest becomes a reality between the two.