" Soon enough, Nifeleim will prosper like it never has before. And the name of Hagall-Sama will be known as...the greatest Damaikaichou."
She is an attractive blonde demon, with purple markings in a flamboyant yet revealing dress.
When she is first introduced, she and her companions easily overpower Hild, due to her belief that Hild has lost the power and glory needed to rule the demon world. Following the coup, she assumes control of Niflheim (Hell), and quickly initiates an elaborate plan to get more share of wishes on Earth and to destroy everything related to the Goddesses via hostile takeover of the shares on Earth, disrupting the balance between Heaven and Hell.
With the real Hild imprisoned in Niflheim, Hagall sends her servants to attack Chibi-Hild on Earth, only for her to escape and approach Belldandy for help. When the Goddesses and Keiichi arrive in Hell, she orchestrates a series of challenges, wherein they face off against her allies to advance.
After seperating Keiichi and Belldandy from Urd and Skuld, and forcing Belldandy to use up all her powers, Hagall attempted to turn Belldandy into a demon, only to be outfoxed by Keiichi with a little help from one of Hild's Chibi avatars, the two negating their previous contract before making a new one, the resulting comotio giving Keiichi the opening he needed to get close enough to Hagall to whisper in her ear, allowing Chibi-Hild to possess Hagall and force her to release the real Hild from her restraints.
Later it was revealed her coup was simply a ruse and she's always been loyal to Hild, having been saved by her as a child, along with her allies, and trained to use their unique abilities rather than 'traditional' Demon Powers. Her true aim was to create an ideal world for demons before Hild's Term of Office could come to an end, as the Daimakaichou's life would end along with it.
Hagall usually talks about herself in third person and her powers include mental control and hypnotism. She is a very selfish and ambitious demon who does not consider the energetic balance between Heaven and Hell (brought by human contracts).