Origin
Forests
They’re a type of elemental that dwell in trees, and they’re called “Demi-Elementals” since they were originally born as monsters. They nestle close to a single tree for their entire lives, and when the tree dries up, their lives end, but the trees they dwell in can keep living for thousands of years by continuing to suck spirit energy from men. Due to their rich demonic energy, they can protect themselves from searing flames and bad diseases that infect trees. They’re normally warm, but they will attack those who threaten the forest without mercy. With vines that pop out of the ground, they can bind the man and throw him to the other monsters that are starving for sex. They are extremely passionate about romance. They seduce men they like, imprison them inside the tree, and then have sex with them inside. From the outside, this just looks like the dryad is coiling around the tree, but in spite of how it looks, there is a hollowed out area inside of the tree that is spacious like a house. Unlike what it seems from the outside, the man inside is furiously having sweet intercourse with the dryad and is enjoying her sweet bodily fluids. Men who are shut inside the tree for a long time eventually fuse with the tree. Men who end up like this cannot die until the tree dries up, just like the dryads themselves. Unable to escape, they’ll just continue to be loved by them.
Monster Girl Encyclopedia