Gokumon Nadeshiko Koko ni Ari

The Gokumon clan - a bloodline from hell. Living in their mysterious stronghold in the ancient capital of Kyoto, they command fear not only from those who wield magic, but also monsters and demons. Nadeshiko Gokumon is the monster-devouring heiress of this wicked family. She is the most beautiful, and the most abominable, girl who comes straight from the flames of hell.

However......
"Nadeshiko, I see you are as lovely as your name."
The encounter with the most strange, disturbing, and beautiful woman, Amana Ichijiku, who laughs in her face without fear, changes Nadeshiko.

Something lurks in the flower ceiling. A human sacrifice packed in a box. A curse that threaten the school. A deceitful beast. A shapeless monster. As the two confront one supernatural challenge after another, they eventually come face to face with the very thing they have been turning away from.

"If it weren't for you, I would still be an ogre."

A woman with a human soul in an ogre's body and a girl with a monstrous soul in a human body. The connection between the two is a story that will be sealed with blood.

(Source: Gagaga Bunko, translated)

Note: Winner of the Grand Prize in the 17th Shogakukan Light Novel Award.