I'm trying to find an old classic cat girls hentai manga I guess it's about a cat who gets reincarnated as a Cat girl and she goes to her former owner whose a playboy teacher. I remember the beginning is she barges in on him fucking a student, he "rapes" her as punishment for being a cuckblock. I also remember the running gag of the manga is she always bites his balls when he tries to get a BJ from her.