In the 1999 anime, she is voiced by Yumi Kakazu best known voicing Anzu Mazaki from Yugi-Oh first anime series. However, in the second adaptation of the anime, she is voiced by Yoko Hikasa who is best known playing the likes of Rias Gremory from Highschool DxD, Freya from Danmachi and Akiyama Mio from K-On.
In both manga and 2018 version of the anime, Dakki is described as a beautiful and busty woman with long pink hair with bewitching blue eyes. While she always changes her clothes all the time to several ridiculous and avant-garde fashions, Dakki's most consistent costume is that she wore a white swimsuit like outfit, white boots and a ridiculous red and white hat that were usually used by the Priestess class in several RPG games. This was intentional as Dakki's appearance mirrors the symbol of the decadence and depravity the Yin Empire has fallen into due to her manipulative nature and her job seducing the Yin Emperor to get what she wants while enjoying the lavish life that she had.
In 1999 version however, this version of Dakki wore a more modest outfit compared to the provocative version of the manga and 2018 anime version with shoulder pads were added in her outfit and her colorshift of her outfit being changed from white and red into being dark purple and white. Her hair color and eye color are also changed in the 1999 version as she has gingerish brown hair color and brown eyes. Regardless of her modest fashion, her appearance is rather fitting for her role as the Evil Empress of the Yin Empire due to the royalty like nature that surrounds the clothes' color scheme.
Overtaking So Dakki's body (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, 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 will 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.