looking for a manga

i read a manga [a couple months ago] abt an orphan girl who had a childhpod sweetheart [guy] who is also an orphan—but, the guy was adopted earlier than her and she wasn't adopted until she was [16] or smthn. but—what she doesn't know is she's getting adopted by the same family that adopted the guy!

turns out—the family adopted the girl to be their sex slave? and the guy was also a sex slave × butler typa shit? and, of course—the girl seeing that her childhood sweetheart was turned into some kind of prostitute, ur girlie was flabbergasted.

but, then—since she was now officially the family's sex slave, the two brothers who were legitimately from the family were taking advantage of her and [rapping] here anytime and everywhere?

but, then—the much younger brother actually falls in love with the girl and helps her to escape and be with the guy—however, the much older guy finds the girl and she was taken back to her house again.

but, this was actually a plan of the older brother to bring the guy and girl together—because, their father wanted the much older guy and girl to marry? and although the much older guy had fallrn for the girl. he knew that the girl would be much happier with the guy.

and in the end—[i know this is fucked up], they all had some sort of foursome together?