Sex Drop
Complete | Shikke | 2000 released
Don't understand why it has such a good rating... It was just okay Apparently this is continuing.. should reread if its completed
Kurui Naku No Wa Boku No Ban
Complete | kusabi keri | 2016 released
has sequel basically the whole company and the business partners have (group) sex with this one guy (the omega)
Bicchi na Neko wa Koukishin ni Katenai