This is a description of using 48 different techniques to stimulate the nipples of female college students on the street, aiming to develop their nipples into highly sensitive ones. The text mentions using fingers, tongue, penis, and toys among other methods. It uses "さきちゃん" as an example, describing her journey from embarrassment to gradually enjoying the sensation, ultimately making her nipples extremely sensitive, even reaching orgasm just by having breath blown on them. Finally, it mentions internal ejaculation, but due to the intense pleasure from the nipples, she might not have noticed it.
