It is embarrassing to admit but I used to think I really had dog ears and a tail until I was about 16.

Well, at least older students found it completely adorable when I made noises...and the school authorities thought I was like smart or something and didn't really care either.

I don't really know the cause, I don't remember knowing about kemonomimi until a bit later but I had delusions not only about seeing these body parts in myself but also felt them. I thought I broke my tail once, for example.