Kurozuka is the most well-known demon woman in Japanese folklore, and a very popular subject in the arts, starring in everything from paintings to ukiyoe prints to noh plays. She has gone by many names. Kurozuka, or the witch of "the black mounds", is the most famous one, but she is also known as the Demon of Adachigahara, or even just simply Onibaba, "the demon hag".

Her story has changed over the years and through various adaptations. A popular version of the story goes like this:

Long ago, a wealthy noble couple had a daughter whom they loved very much. However, their daughter was sickly, and by the age of five she had still never spoken a single word. The worried couple consulted with priests and doctors, until finally one doctor told them that the only way to cure their daughter was to feed her a fresh liver from an unborn fetus.

The couple summoned their daughter’s nanny and put the task of retrieving the liver to her. Expecting that it would take some time to find someone willing to give up their baby’s liver, the nanny prepared for a long journey. She gave the daughter a protection charm and promised not to return without the liver, then left.

The nanny traveled for days, months, and eventually years without finding any family willing to give up their baby’s life. Eventually, her travels brought her to the moors of Adachigahara, in Fukushima. Despondent, she decided that if nobody would give her a liver, she would have to take one. She made camp in a cave off of the toad and decided to wait for a pregnant woman to pass by.

Many more years passed, and finally a lone pregnant woman came walking by on the road. The nanny leaped out of the cave and slew the traveler with her knife, carving her belly open, killing the fetus, and taking its fresh liver. Only after the deed was done, the nanny looked down at her victim, and noticed the young woman was wearing a very old but very familiar protection charm: the very same one that she had given the daughter so many years ago! The knowledge of what she had done weighed so heavily on her that the nanny went insane, and transformed into a yokai.

The Demon of Adachigahara developed fearsome magical powers. She learned to lure travelers into her shelter and invite them to spend the night, after which she would murder them in their sleep. She remained there on the moors of Adachigahara for many many years, murdering any lone travelers who passed by her cave and eating their remains.

In the noh version of her story, the demon woman is eventually visited by traveling Buddhist priests, whom she plans to kill. While she is out gathering firewood, the priests find a room full of dead bodies and bones, and they recognize her as the Demon of Adachigahara. She chases after them, but they are able to hold her back with their Buddhist prayers, and drive the evil spirit from her, banishing it forever. When the demon spirit is driven from her body, she becomes an old woman and dies. The monks bury her remains and build a grave among the black mounds where she haunted.