My sister, a high school girl who diligently massages her breasts day and night in hopes of making them bigger, but they never grow! Instead, with each massage, the stimulation to her nipples, which she unconsciously touches, feels good, and she gradually becomes obsessed with 'nipple teasing'! When I accidentally witnessed my sister's nipple teasing onanism, I naturally got a full erection! Unable to calm down, my sister became very interested in my penis, and I couldn't hold back either, leading to us engaging in forbidden incestuous sex with my sister who was extremely sensitive!
