Naoki Himura was the owner of a house where a Soul Eater was trapped.
She accidentally set the monster free by scratching out a Celtic Monster Trapping Sigil hidden behind the wallpaper, leading to her daughter being put in a coma.
Naoki later told people of what she believed to be a supernatural occurrence in her house, but no one listened. Thankfully, help came in the form of Sam and Dean Winchester, posed as FBI agents who questioned her about the attack. When she described cold spots and electrical disturbances, the brothers assumed a ghost was in the house. Naoki gave the boys permission to search the place.
The next night, Naoki was attacked by the Soul Eater and her soul got trapped in its nest. Thankfully, Naoki and Kat were freed when the brothers killed the Soul Eater, restoring their souls to their bodies and waking them up. Afterwards, Naoki reunited with her wife and daughter, and decided to sell the house.
- It's revealed she has a wife, making her a LGBT character, during the phone call that Naoki has with her wife at the beginning, as she calls "I love you too Maya", referring to her spouse.