The Billionaire's New Wife in Chief - Chapter 1029 - 424: Chu Munan Is Here Too

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.

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates

Jin, a guy with no direction in life, through an unfortunate event gets his hands on a Hitman System. What transpired then was a struggle to escape the eyes of the cops while trying to complete the system’s missions. However, through a series of coincidences, he soon finds out that his parents’ death was not an accident. Read how he uncovers the veil that has obscured the truth from his eyes since childhood and finds out the darkness that hides under this veil. ‍

There was a time where I was summoned to a different world. I spent more than a year as a Priestess from a different world. I fulfilled my role and decided to return to my original world. Before leaving, I confessed my feelings to my escort knight. And from there I was heartbroken. After returning to the original world for a year and half, I was summoned again. What? Apparently this time, nobody summoned me. I was sent out to a great extent and have a lost love. I cannot face anyone now! No one knows that I was a former Priestess and I can only quickly return to my original world. Even so, it does not seem to work out very well…