maybe this?
http://www.mangago.me/read-manga/caste_heaven/
slavery of demons
http://www.mangago.me/read-manga/itsuwari_no_mori/mf/v01/c001/
http://www.mangago.me/read-manga/yurusareta_uta/
this has multiple stories with couples that know each other so not all of them have the uke with the status
http://www.mangago.me/read-manga/yurusareta_uta/
slavery of demons
http://www.mangago.me/read-manga/itsuwari_no_mori/mf/v01/c001/
http://www.mangago.me/read-manga/yurusareta_uta/
this has multiple stories with couples that know each other so not all of them have the uke with the status
http://www.mangago.me/read-manga/ze/
I didn't mean to post the same link. lol
this one is kind of cute too
gardener is the seme and rich master is the uke
http://www.mangago.me/read-manga/kayashimashi_no_yuuga_na_seikatsu/
Okay, I'm not looking for any manga in particular, but I want something that has a ranking system, and one guy protects another guy in the system. The protector has to be an uke, and the seme has to be the lower rank.
It can be anything like companies, schools, and cities, but the one I want most is slavery! Thank you!