After school, cute girl students among friends are teasing a boy's erogenous zone, the nipple, which wasn't taught at school, until it's melting soft. The boy, sensitive to his nipples, reacts with twitches and excitement. "His nipples are getting huge just by touching them!" they exclaim. They lick, masturbate, and play with his nipples, leading to an uncontrollable outburst. It's non-stop nipple teasing, resulting in a reversed threesome. The focus remains solely on teasing his nipples throughout the wild, internal sex in a harem setting.