"According to an old research journal, a Darknut is a large canine sub-beast that served as a sentinel in the Arbiter Grounds to keep inmates from escaping. They've been extinct for many centuries, until a scientist found a weapon once wielded by them, the Arbiter Spear. When the weapon was exposed by the Ether, sand appeared around the spear and out merged a female Darknut. She claims herself as the reincarnation of the Eighth Heroine of the Desert, the people of Gerudo called her Anubis, the Queen of Death."
— In-game description