Gokumon Nadeshiko Koko ni Ari

Gokumon Nadeshiko Koko ni Ari summary:

The Gokumon House, a bloodline originating from hell. Within the mystery-filled ancient city of Kyoto stands their citadel; they are feared not only by the seedy underworld of sorcery, but by monsters too.
Gokumon Nadeshiko, a descendant of this cursed family, is fated to devour monsters. A most beautiful girl, born from the flames of cremation; her very being brings about bad omens.
However... "Nadeshiko. I see. You are as lovely as your name." Ichijiku Amana, a most peculiar, mysterious, yet gorgeous woman. Their encounter changed Nadeshiko as Amana faced her with a fearless smile.
An creature lurks in the painted ceiling. Boxes packed with human sacrifice. A twisted curse upon a school. A beast who deceives humans. Haunted by a formless ghost. As the two are faced with one mystery after another, they are ultimately confronted by what they tried to leave behind.
"If it weren't for you, I would've remained an Oni."
An Oni with the heart of a human, and a human burdened with a corrupt soul. The bond that they form will cut the seal on this blood-soaked tale.