A naive girl who walks a little apart from her classmates on a factory tour can't refuse when an old factory worker tries to do something naughty with her! !

Naive students come to see a small factory on a social studies field trip. A girl is so curious about the machine she sees up close for the first time that she wanders out of line. Oil-covered factory workers secretly play naughty pranks on this naive child who is a little out of place. The cries for help are drowned out by the sound of the machine, and an extracurricular class for adults begins in the blind spot of the large machine...