Nagisa is a growing girl. One day, when she enters her brother's room, she finds a pornographic magazine that he forgot to put away... "Big brother, do you like girls' breasts?" Nagisa shows her breasts to her brother when he returns to the room. Her innocent act causes the brother's reason to collapse. The perverted brother thoroughly caresses the body of his innocent sister who is weak to pressure! This is the secret record of a brother and sister growing up to be erotic...