Just found this and it's so damn good.
https://exhentai.org/g/3033459/5b9810aac1/
>girl is caught by a futa demon
>demon declares she'll turn the girl into a hucow
>repeatedly casts charm magic on the girl's eyes and breasts while coaxing her that becoming lifestock is great and she'll get milked every day
>eventually the girl succumbs and they live happily ever after with lots of milking
The dialogue is really erotic. Might try translating later.