A soapland where beautiful girls only come to work on their dangerous days, is frequented by men who want to impregnate them. Rika, who has a small body but soft, large breasts, has a customer...her own brother!? He is confused, but he has incestuous sex with his brother who is turned on by his real sister! He even has cosplay sex while wearing the uniform from his school days when Rika was an honor student! The merciless creampie ensures that the brother and sister conceive and become pregnant!