I'm searching for a manga I accidentally found years ago.
At that time it only had 1 chapter, plus it's been too long so excuse me if I'm a bit vague.
All I remember is that main characters had literal master-servant relationship, master (MC) was a rich teen while the servant was something like his butler/bodyguard of same age and he was always expresionless.
I remember one scene where MC master is having sex with girl whom he met on a group date, while the servant is watching. Master tells him to have intercourse with girl because she was so horny that she'd take both.
In the end MC's family lost all money while servant's family got rich so now that servant shoved him in so me room and told him that now MC belonged to him.
I hope you'll be able to help.

Devil x Devil chap 5, I think.

Bless you, that's exactly what I was searching for.