Stamen and pistil are penis and pussy. The innocent student plays with the older sister's braless nipples while asking questions! The student, who doesn't know how to masturbate, teaches her how to masturbate, how to gently touch breasts, and what a pussy is, in a gentle and erotic way. A serious lesson at the mercy of a precocious student. When the older sister loses her senses due to the student's prank, the lesson turns into an erotic one!