Somewhere in the middle of it all, FNAF's designs began to show what was under the shell -- beneath all the fur, metal and clothing parts. While the interior has been classified as an endoskeleton since the beginning, Freddy's Five Nights: Sister Location is when we really experience these particular atrocities. Take Yandu for example. Yendo is a furless, naked version of Freddy, except that "underneath" is an eerie metal tube of muscle tissue. His first appearance was also a small, random encounter, which added to the tension.