Sex and prostitution is implied, but no acts are shown.
To clarify, there's no actual human nudity in the show. However, there are these androids called Thirds that are known for looking and acting human and they are sometimes seen bare naked. Genitalia isn't shown, but bare breasts with non-detailed nipples (similar to a naked mannequin) are shown. We also see X-rays of these androids that reveal the metallic plating that makes up the artificial breasts, as well as some of the wires underneath.
This OVA is rated 16 Up.
The third poster of this series has her breast shown. Inside the memory banks, a woman was naked. A man quietly moans before the other man pulls the plug.