https://www.dlsite.com/books/work/=/product_id/BJ217523.html
As always, please support the artist and buy his works.

Don't fuck! Sex Manners Course taught by a vagina - A cock so big you can't measure it!

Rin Hirose, a fledgling manner consultant, visits the residence of a large corporation.
What awaited her there was Akito Misono, a sarjeant with a problem that causes lecturers to quit one after another!
However, he looks and acts like a polite young man, so Hirose begins her lecture, wondering what the problem is.
But when she starts taking measurements to make a suit, he shows Hirose his big, stiffly erect penis...?
He then asked her, "Would you like me to measure this part as well? Akito starts to play with Hirose's crotch as if he is torturing her, and finally he inserts his big cock into her vagina...!
Hirose can't resist him now that he has taught her the manners of sex...?