I NEED TO FIND THIS MANGA

So like said in the title i need to find this certain manga i'll get straight to the point
So there's this officer worker i think who finds a stray 'cat' which is not basically like an alien he adopts the 'cat' and takes care of it until he realizes what he has brought in nevertheless he still took care of it. And so the 'cat' feature details is that they have one eye and has a REALLY dark body almost as if its body is a void and its weird looking, i don't remember the details much bc its been a long time i read it so i basically forgot almost the entire thing except for the character details. if you find it and reply to my question thank you so much