http://www.mangago.zone/read-manga/rakuda_tsukai_to_ouji_no_yoru/ (Story 2)
http://www.mangago.zone/read-manga/black_sun/an/black-sun-chapter-1.html/
These are the only ones I knew that are close enough. I'm sure there are entire lists of these.
just a oneshot but it's still good. http://www.mangago.zone/read-manga/harem/
I have my own collection. just check my notes, I've put the pairings there http://www.mangago.zone/people/tag/49344/royalty%2Fnobility/
also, black sun mc is about generals not nobles. (the uke served as a slave the whole duration of the story so it should not count)
Thanks guys :-)
Iìm looking for a yaoi with a prince,king or something like that have guys like concubine or so that he use at night!!!