The storyline with the girls will probably mostly feature only you and the girls, except corruption routes could have other men starring in them if it suits the route. But I don't know, honestly I haven't planned in that much detail yet to give you an answer that's set in stone. But if there are more males, it should be pretty easy to avoid them if you want to. Especially if you go the love route, which probably won't have other males in them.
Of course, there will be male side characters, but they won't necessarily be in a sexual role, like Kyle Diller in the most recent update. And I'd like to offer the player the choice of what to do and who to share whenever possible. So, there will be other content besides just prostitution, but ofc it would be ideal if you'd like both lol.