Younger sister with small breasts and older sister with big breasts. One day, the younger sister realizes that her older sister has super sensitive nipples. She rushes into her older sister's room who is secretly doing nipple masturbation, and nibbles, licks, and sucks! In no time, she is made to cum by her younger sister's tongue technique and becomes a weak nipple! From then on, every day she targets her older sister's nipples! While laughing, she plays with her older sister's nipples and develops them every day! The older sister becomes so sensitive that she orgasms from just a little stimulation, but in the end, she turns around and... her younger sister's nipples.