I'm very new to Mmd, and I am trying to figure out how vagina/anus work on a model. I've seen people's models, and in the patch notes, they refer that those body parts work somehow. At first I assumed that there must be some sliders to control these parts, but I turned out to be wrong. I also noticed something weird (the insides of the vagina exist), and I think they exist for some reason. Could anybody explain to me how these body parts actually work? I'll very much appreciate any kind of explanation!