So the manga is about a guy clearing conquests of girls. He has a menu option and the girls have difficultly ranks. Also along the way he finds this girl with black hair that is very dangerous because shes part of a wealthy dangerous family. Also some extra details he also assist this women with a sword. Also he has special items like a sword that blocks attacks and can save and load at anytime.

found it, the name is Ore no Genjitsu wa Ren'ai Game?? ka to Omottara Inochigake no Game datta