After a Geisha was Stripped of her clothes it is then implied that she was Sexually Assaulted by the same man, but nothing is shown only implied.
A woman reaches under another woman's kimono to see if she had a sexual encounter. She pulls her hand out then slaps the other woman, affirming her suspicions
It is implied a woman's sister became a prostitute
A quick scene of a geisha having sex with her boyfriend (only a few thrusts are shown with him on top and a blanket covering them).
The theme of selling yourself for entertainment is mature even though Geisha traditionally did not engage in sexual congress with their clients. Doing so was below their dignity and left to common prostitutes. A woman loses her virginity which the person has been bidding for.
A young geisha is gradually stripped of her clothes once being forcefully kissed. Her bare back is seen.
A geisha suspected of having sex is handled roughly by another woman, implying non-consensual touching.
A geisha has sex with the American Army Colonel, but nothing is shown except for her bare shoulders.
The geisha are seen in a natural hot springs pool with other men, you cannot see full nudity, only the shoulders and just above the women's chest.