Mc is a loli that living alone inisde a mansion, she have a black cat but that cat actually ded n some strange creature pretend to be that cat. Oh, and there is an old man that always drawing a line along the road. And If u cross the line, monster will show up and eat u. I think mc hair turned white because that thing.

Most likely Kuro (Somato)

It has everything you listed

Thank you man. I have a bad memory... I keep forgetting everything these days