A fantasy world where Humans and Cats don't exist, but instead, Catgirl and Catboys do.
For the cat part, Neko's have a long tail, cat ears instead of humans ears, cat-like pupils and whiskers. The rest are human body parts.
Many cat stuff are normalized. Catnip is an illegal drug, yarn balls are stress toys, petting someone is a kind move, while petting someone's tail is an intimate, sexual move.
Humans and Cats are an unknown concept, because they didn't exist at all. While others still exist.