While his father was at work, Yoshikazu accompanied his mother and relatives to a hot spring. After a long absence, he is captivated by the unobtrusive intimacy and voluptuousness of his aunt Rei ...... Rei also happens to catch a glimpse of her aunt's young, powerful penis and locks her eyes on it, using it to release her husband's insatiable daily sexual desires. Rei awakens Yoshikazu's desire for sex, and he approaches her again and again with the same frantic ape-like passion...