Plot Summary

My older sister's big boobs are growing so much that I feel they're getting bigger every day! One day, my sister suddenly asked me to "massage my breasts!" My breasts grow and become swollen and painful, but it seems that there is a sense of incongruity when I massage myself. When I rubbed it all the time, my sister's face started to get angry and went into erotic mode! I can't stand it even if I know it's my sister!