Kobayashi is a sex instructor who has been assigned to a school for rich girls where sexual intercourse is compulsory but where sex education is lagging behind. He enjoys a fulfilling life as a sex instructor, devouring innocent girls as he pleases under the guise of instruction. One day on a day off, he goes to the school where he was previously working. The documents he is handed include two girls. Seeing them, Kobayashi is reminded of those days. Starting with the first instruction, the instruction is repeated almost every day, regardless of location. He opens the door with the memory of doing as he pleases and finds the two girls with big bellies. Now, instruction for the two girls with their big bellies begins.