Dakki (蘇 妲己) is the main villain of Houshin Engi.
Overtakng the body of So Dakki (a young woman who was brought to the imperial palace to be Chu O's 200th wife), Dakki the Sennyo bewitched the Emperor with the aid of her spell of Temptation. Chu O became nothing but a puppet in her hands, doing exactly as Dakki pleased and having very rare moments of sanity. The vixen demon is 5,000 years old, very beautiful and intelligent to the point when she could be labeled as "genius" (with her only intellectual rival being the protagonist, Taikoubo). In the manga, her character is more complex, but in the anime, she is pictured as the evil, selfish Empress who wants nothing but power and cares only about herself and her two sisters (not blood related, however) Ou Kijin and Ko Kibi.
She is capable of using multiple paopeis at once (ex: two fans, the Veil of Temptation). Her most important paopei is the Veil of Temptation and she is rarely seen without it. It emits a strong scent which affects all men and bring them under control. In order to resist the spell, one needs an iron will. After her descent into the Human World, she took many names (Ou Shi, Bakki) and seduced the leaders throughout history, living in luxury. At first, she was content to throw extravagant and expensive parties, but after several hundreds of years, she mastered the Temptation spell and began her reign of cruelty.
Dakki obviously enjoys other people's torment. She even built torture devices like the Horaku or the Taibon (a pit full of poisonous snakes). She is a very good actress and is capable of hiding her emotions. Another ability would be her good knowledge of human psychology. In the manga, when Chu O's first wife was imprisoned, Dakki knew the woman could not stand the pressure any longer and allowed the guard to give the true empress anything she wished for, knowing that she would ask for a dagger in order to commit suicide. She predicted Bunchu's reaction when Ko Hiko left Choka. Bunchu and Hiko were friends and Bunchu would rather kill Hiko himself than let Dakki decide how and when it would be done.
She shows sympathy only to her sisters and to her adopted son, Ou Eki/O Tenkun. Cruel as Dakki might be, she is not be entirely evil in the end. In the manga, the reason Dakki worked for Jyoka was, at first, due to her desire for power. But after she learned about the Ancients and that they fused with the planet, she was deeply affected and so her secret goal became to obtain Jyoka's body so she too may become one with the world. In this way she was able to save Taikobo at the end.