400 years ago, the Nura clan was starting to become the most fearful group in the land, they're different from the others because their protecting humans as well as gaining fear from the Yōkai clan's and Ayakashi that live to eat the liver of a new born babies, priests, priestesses and noble persons.
In this era, there was a beautiful princess named Yōhime, she is said to be God's gift because of her power to cure any kinds of disease. The princess' power was abused by her father; all people that wanted to get cured needed to pay high amounts of money, because of this, Yōhime was unable to see the outside world. Soon enough the news spread, she became the new target of Kyōto Yōkai. They wanted to offer her liver to their master Hagoromo Gitsune.
After one yōkai nearly succeeded, Yōhime's bodyguard Koremitsu gave her the exorcist's blade Nenekirimaru to use for her own protection. Nurarihyon heard about Yōhime and became interested in her, he went to Yōhime's place and proved that rumors were true: she is beautiful and can cure wounds.
When he stated his desire to "have her", she mistook it to mean he was after her liver as well and managed to cut a gash in his arm with Nenekirimaru. The open wound startled Yōhime, and she immediately used her power to heal it, much to Nurarihyon impression . Every night Nurarihyon went to visit Yōhime. One night Nurarihyon took Yōhime outside the mansion and went to their hideout, to introduce Yōhime to his comrades. To their surprise, Nurarihyon asked her to become husband and wife, much to everyone's shock. Yōhime does not answer, instead said not to go again in the mansion. Next night Yōhime's mansion was attacked by Yōkai, and all of the Onmyōji looking after her were killed, only one survived. Nurarihyon arrived wondering what happened and he found out that Yōhime was been captured by Hagoromo Gitsune's clan.