This is Aelfée – The (Dark Elven) Monster Girl.
The Dark Elves weren't naturally monsters. They were one of the non-monster intelligent races, along with humans, dwarves, fairies, and high elves. After a certain incident in the Chaia Island, dabbling with a certain magical experiment that lead to the opening of a chaotic demonic gate. Corruption seeped through it driving them mad with pleasure and lust. This lead to their skins turning pink/purple as an indication of corruption exposure. They eventually started to worship the Succubus Demon Lord.
Upon Succubus Demon Lord assumption of power, the Dark Elves, who were lustful and uninhibited by corruption to begin with, offered their own bodies to the Succubi and changed into monsters, as they became an all-female race from that day onward. They don't detest humans as other elves do, but they love to make human men who strike their fancy submit to them using pleasure. They even say that Dark Elves can use magic to temporarily turn their skin white/light and may do so to trick humans into slavery for reproducing. However, they will want him to love their shaded skin as well.
They are crafty, you should tread carefully around them.
