On a packed train, a series of voluptuous women with erotic areolas are targeted one after another. Using fingertips, tongues, and toys, their previously undeveloped nipples are stimulated, growing increasingly sensitive. Overwhelmed by intense pleasure, their nipples react like clitorises, climaxing repeatedly despite their inability to make a sound. As their arousal deepens, they grow more lewd—eventually craving the stimulation themselves—unfolding a nipple-focused erotic experience like no other.