A powerful dog demon and Sesshomaru's mother, was introduced in the 466th chapter of the InuYasha manga. She appears in the episode 9 of InuYasha: The Final Act.
Sesshomaru's mother is an inuyokai like her deceased mate, the Inu no Taisho. As such, she can transform into a giant dog demon as well as having more human appearance. She holds the Meido Stone, which was given to her by Inu no Taisho. He told her that if Sesshomaru were to come by, to use it and "If you use Meido-Stone Sesshomaru will be faced with great danger... However, you must not feel fear or sadness." This apparently was another of the Great Dog Demon's tests for his sons.
In demeanor she seems similar to Sesshomaru, albeit with a certain playfulness, and probably influenced his initial attitude towards humans; observing Rin and Kohaku following Sesshomaru, she inquires casually if he is planning to eat them. Observing Sesshomaru's trial after activating the Meido Stone, she seems at best only casually concerned about the possibility of his death, and after he refuses the escape route she offers, she seems mildly offended, complaining that, unlike his father, he "completely lacks any charm."
However, she does feel concern for her son's well-being, as seen when she brings Rin back to life using the Meido-Seki after witnessing his reaction to her death, and later when she questions Jaken in whether or not Sesshomaru was happy now that Rin was brought back. She appears in episode nine "Sesshomaru in the Underworld" of the second anime series "Inuyasha: The Final Act."
Although she is a daiyoukai, she is shown to have a good heart, chiding Sesshomaru for seeking to perfect the Tenseiga as a weapon of destruction rather than a weapon of healing. She also lectures him about the qualities of the wielder of the Tenseiga, emphasizing the need for compassion, love and a pure heart. This could mean that she bears no ill-grudge towards her former mate; rather, she still nurses deep feelings towards him. She also stays in a large castle.