A letter from my beloved brother saying "help me". Taking this opportunity, her sister returned to her parents' house for the first time in seven years, and what she saw was a strange figure of her mother-in-law who was pleased with her brother's sexual teasing. A younger brother who is made a toy for her mother-in-law's twisted propensity. In order to protect her beloved brother and teach her true sex, her older sister uses her own body to practice her true sex education.
