Sexy Isekai: One Piece Most Wanted - Chapter 6 - : Sweat Drop! R18+

It’s a story about a man who got transported into a novel and possessed a slum boy. He met a noble girl and served her as a butler for 13 Years. Now the girl has already fallen from her noble life and lives in an abandoned mansion with paralyzed legs. Why did she become like that? Of course because she is the villainess in the novel.

The world is terrorized by the powerful Black Witch who has been sealed in the moon. Every ten years, the night of Hexennacht arrives and a chosen witch must battle the Black Witch in hopes of finally defeating her.

As the current decade’s Hexennacht approaches, a mysterious girl named Kagami Kagami arrives and meets Horinouchi Mitsuru, the daughter of the previous Hexennacht representative.

It takes place between Kyoukai Senjou no Horizon and the City Series, two other series by the author.

“Is this man not going to divorce me? Why does he still ask me to warm the bed every night?”

Coming from the modern era, she was sent to a strange world. The body she possessed previously belonged to a young woman whose family was thrown away by their clan. However with the “Dan Fu Zong”, the inheritance from her old world, she steps on the path of cultivation, hoping to one day become an immortal.

- Description from Novelupdates