That's fucked up, wouldn't call it NTR because...that's his Mom, is she not supposed to be with anyone, but the way she goes about it, she takes it too lightly, the conflict seems dumb for comedic purposes (their loot is cards for a game) and she tells the son about her sexual escapades?

I have seen worse "comedies", like this one, which I wont' ever read

>GraPara!
>A clueless gravure geek, Sumida Shinobu, starts living together with a fledgling gravure model, Kuzuki Sakura, by chance. While he is excited about his dreamy days, a dirty photographer, a corrupt manager, and a sexually harassing producer all come after "my darling Sakura-chan" one after another! Can Shinobu protect Sakura-chan's chastity?
>An NTR love comedy between a geek and popular gravure idols.