I am currently searching for a book (could also be a web or light novel). I read the story about a year ago. Its about a girl who got transported to another world or perhaps the future. There she discovers that humans have gone extinct and the animals have developed human like characteristics.
She picks up a leopard cub who is injured. She meets a deer who promises her to bring her to a turtle who might know how she can go back. The cub turns out to be the chief of the leopard tribe and he was just small because he was injured. He can transform into a very human like body. As if she was his possession he takes her back to his tribe and tries to quite forcefully “mate” with her. She tries to run away but fails every time. I think in the end they fall in love and even have a child but I am not sure about that part.
I don‘t remember more.