According to some Indian folk tales, Yakshi is a type of succubus. It waylaid unsuspecting men who happen to cross its path in guise of a beautiful woman and killed them by drinking their blood. A yakshi named Neeli had become a terror in a place called Vamanapuram. She killed around 1000 travellers in that manner. As the blood count started increasing the local king invited a powerful practitioner of dark arts named Raman to end her terror. Raman succeeded in taking Neeli with him to his house by casting various magical spells. He informed the king that Neeli would not trouble people any more and that he has destroyed her. The king was overjoyed and gave a lot of gold and other precious gems to Raman. Due to this success, the name and fame of Raman, the magician had spread far and wide.
But this success had come at a great personal cost and risk to Raman. The yakshi which he had captured would come in front of him naked every night as the clock struck 12.00. As per the agreement between him and yakshi, he should control his sexual feelings. He can do whatever he deems fit with the yakshi, sexually or otherwise, But if he is unable to control his desires and if he ejaculates his semen, the yakshi would win and would get freedom from the magician. On acquiring freedom in this manner, the magician would become the slave or in worst case can even end up dead.