Amiri-chan is a cheerful, meddlesome gyaru sister who deeply adores her older brother. When she finds out he's finally got a girlfriend, her concern begins to grow—can he kiss well? Is he gentle during foreplay? Can he thrust passionately? Worried about her brother's happiness, Amiri-chan decides to take matters into her own hands. For both her brother's sake and his relationship, she resolves to teach him the fundamentals of sex. Her passionate dedication and pure love deepen the story, leading to intense lessons in blowjob techniques, creampie sessions, and intimate sister-brother encounters that blur the line between guidance and desire.