Previously, a young shepherd was possessed by a succubus. Like most demons, it made the girl taller and prettier in order to achieve its goals. It hid in the girl's hometown and continued her work as a shepherd. When the right moment arose, she would lure her target to a secluded area for pleasure. But instead of sucking its partner completely dry, it would only take a minute amount of life energy. Because of this, she stayed under the angel's radar and lived peacefully in the town.
However, as the months passed, its power grew steadily. Soon, its aura had caused the entire town to be put under her mind control. Only then did the succubus revealed its true color, abandoning its duty as the shepherd and began seducing the men in masses. Tens turned into hundreds, and hundreds turned into thousands. Eventually, a full year had passed since the innocent shepherd had become possessed, and it remained undetected throughout that time. Now, the girl had been fully fused with the demon that possessed her, become a new demon that was much, much stronger than before.
The small town could no longer satisfy this new demon, so, for the first time, it took to the sky and flew towards the big city.
It knows what it wants.
Note: In case you wonder where this character is from, she is from Succubus Takeover (Old Collection 2).