The third challenge between a big-breasted sister and a virgin brother! If the brother and sister can even do a sex practice, they'll win 1 million yen! The brother's dick is on the verge of exploding at the sight of his sister's big breasts, which he's never seen before! When the erect dick rubs against her clitoris during sex, the sister's reason collapses!? The brother's dick slides in and the sister's body twitches! Contains 6 pairs of naughty brothers and sisters who engage in incestuous relationships!