There was a male doctor who was invited to a large house (kinda like mansion) owned by a married couple, initially the doctor thought he was invited to examine or treat the husband of the couple because he was old and used a wheelchair, but in fact he told the doctor to have sex with his busty wife who was already wearing lingerie(?), the doctor initially hesitated because he already had a family but finally he lost to lust. In the end of chapter, the sex scene was monitored by the old man using CCTV.
The doujin are not colored and IIRC it has more of 50 pages.