The world of sword and magic where the hero and the demon king fight. Fell — a demon girl, sets foot on the land where humans live with her master the demon king, with a purpose of establishing a friendly relationship with them.
Under such circumstances, despite possessing an extraordinary power as a demon race, Fell is continuously being pushed around by the humans around her.
“A demon becomes a Sister of the religion that’s trying to destroy the demon race…?”
“I became an adventurer, but what do you mean there is no job request in this guild?”
“You want me to serve the customers while wearing such frilly clothes…? I feel like destroying the whole village now….”
Later in the distant future, the diary that Fell wrote during that time will be found in the deepest level of the biggest dungeon in the world, and become a controversy. There are those who call it a bible, while the others call it a forbidden book.
This is story about a demon girl called Fell and her diary, the story of laughter and tears.