Hibiki lives with her younger brother and father. Being considerate of her brother, Hibiki often warns her AV-enthusiast father, "What if my brother sees this!" However, one day, her brother accidentally views their father's AV. Mistaking sex for something terrifying, he turns to Hibiki in tears. To correct her brother's misconceptions about sex, Hibiki decides to use her own body to teach him the truth about sex...
