Skeletons are undead-type monster girls that can be created using necromatic spells or resurrected by Demonic Energy alone. Oddly enough, their closest relative is probably the golem, as skeletons technically constitute 'bone golems'. Along with the alp, they are one of the only monster girls that arise from former males.
Human bones reanimated through the infusion of the Demon Lord’s power. They look like a kind of undead, but since their short-lived body was made through the infusion of mamano mana, they are a kind of golem, made using bone as the material. Or it could be a type of ghost dwelling in the bones. That’s another possible explanation. The opinions of researchers are split. Just as other undead, they retain memories and thoughts from when they were still among the living, but most of them have weak thoughts and a fuzzy sense of self.
When they get hungry, instinct pushes them to wander in search of the mana needed to maintain their body. When they spot a man, their instinct as a monster stands out among their vague thoughts and tells them what they should do then. They'll assault the man and straddle him according to the voice that echoes in their head, and await the arrival of mana while shaking their hips as their bones rattle.
The mana they acquire from having sex with a man in this manner allows them to store up mamano mana and regain a bit of their thinking ability and sense of self. Due to that, new thoughts will occur to them, and they'll then feel that the sex they just had now was "pleasurable" and the mana was "delicious", and they'll have self-realizations such as, "I want to taste more of it" and "I want to violate the man before me." And then, they'll end up having sex with the man before them again to sate the desire that sprung forth. From then on, every time they have sex, the sense that "it feels good" and "is delicious" will swell enormously within them, and the self-desire to have sex with the man grows strongly distinct, eventually becoming the driving force of their actions. Before long, they'll begin to sexually assault the man of their own free will instead of just instinct, and the movement of their hips and the gasps escaping from their lips will change to reflect the enjoyment of the pleasure.
Perhaps because they are ephemeral bone constructs, they don’t have much strength. A strong force can shatter their body, but they always come back together. Once they give chase, they tend to follow you everywhere, so it’s very troublesome. But, once their hunger for spirit has been sated, the self-motivation and thoughts that arose during sex have been satisfied by sex, so they once again become spaced out and grow docile. Once they begin to become spaced-out, the only feeling that remains is the desire to be with the man who poured mana inside them, and it is said that they'll entrust their thinking to the man and follow his orders.
Zombies and other undead type monsters can fundamentally never rise from a man’s corpse; however, in the skeleton’s case, mamano mana doesn’t dwell within the body, the body itself is made up of mamano mana. They are an exception, and men’s bones can become monsters too. Even in that case, the body formed is still a female body. Thoughts and memories from their lives as men remain, but they mostly become twisted in ways such as the following: “When I was alive I was a woman.” “When I was alive, my best friend was my lover.”
There is a class of spells used for manipulating the dead known as “necromancy” but if used when a powerful monster is nearby, in a dungeon filled with mamano mana, or in a mamano realm, it is incredibly dangerous. Upon raising a skeleton, it would be infused with mamano mana and become a monster. After having just been born, she will be very hungry and will probably attack immediately.