The Shogunate's Harem (1986)

A new shogun is appointed to the throne when his brother dies. He find out that the former Shogun one of the women from his brothers harem became pregnant, but she escaped. The new Shogun would loose the throne if the child is a boy. Genshiro is doctor who, among other things, performs abortions, and is sheltering his love, another women who escaped from the harem. The new Shogun threatens to arrest the girl unless Genshiro hunts down the woman and aborts her child. Genshiro learns that the woman releases a "musky scent from her special area" when in ecstasy. Both Genshiro and his friend set out to find all the women of the former harem and have sex with them, by force if necessary.

Unfortunately the movie The Shogunate's Harem is not yet available on HBO Max.