MTL - One Piece: Wudang Baiye, Deputy Captain of the Straw Hats - Chapter 454

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.

He was the cold-blooded prince of the Jin country. Decisive and smart, he had looked down on the world with apathy and disdain.

”When I tell you to proceed with Plan A, you can’t just ignore it and go with Plan B,” said the king.

”Sure”, she replied; she’ll just go to Plan C then! No biggie.

”If you were told to go eastwards, you can’t just ignore me and go in the opposite way,” the king added on.

”Yes,” she said while nodding. If she can’t go in the opposite way, North and south work fine too.

”You are NOT allowed to have affair with any other men!” the king then emphasized.

”Sure”. She replied. She never has to be the one having affair with the others. Others have it with her.

- Description from Novelupdates

Yuki, a high school junior, dies heroically saving a stranger and is reincarnated in a fantasy world, where he discovers an extraordinary and unrivaled power.