Ruefio

Looking for a manga

It was featured in the transformation section and showed a younger boy character with a crush on an older girl who, through intercourse, accidentally changes her into a cow hybrid. It is not a detailed animation but it is evident when she is waiting for him at the end of the manga. I can't remember what it was called and can no longer find it. Anyone have any clues?


additional note: I think the boy was some sort of hybrid already himself