MTL - This Game is Not Easy - Chapter 10 inquire

A surgeon accidentally got the blessings of a system, shocked the medical industry, and rejuvenated countless people.

- Description from Novelupdates

Lugh woke up to find that he had transmigrated to a hundred million years later.

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.

She was forced by her husband and his mistress to jump into the sea and commit suicide, only to be rescued and taken care of by the jerk's uncle for seven years.