Super Invincible Immortal Doctor - Chapter 2: Xu Nanzhi

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.

Thousands of years ago, a small planet collided with Earth and destroyed the world. In five days, ninety percent of humans had been wiped out, leaving behind the last ten percent to earnestly struggle on death’s door.

Jinyu was one of those people who survived. Due to a special heredity trait, he could understand beast language. After the apocalyptic disasters, Jinyu had been living for a month with the few small beast brothers that he’d subdued. Previously, Jinyu had thought that he would live like that until he died. Yet, inexplicably, one day he opened his eyes to find that he was in a monstrous, lawless world that was full of vitality and life.

Jinyu’s transmigration into the future let him skip over almost one hundred thousand years. In the year 106825, beasts rule the galaxies and ‘pure’ humans are extinct. As the one and only ‘pure’ human left in the entire universe, Jinyu braves this new chaotic world to find a place for himself and thus begins to work at Beast Store number 138.

- Description from Novelupdates

This world is sick; both Immortals and mortals suffer from a stubborn ailment known as Longevity.Under the influence of Immortality, various Cultivation Techniques evolve rapidly in grotesque and inexplicable directions.[Fetal Period: A baby is born with shriveled, powerless limbs.][Childhood: After 20 years, the Internal Organs completely decay.][Weak Crown Period: At 50 years, the flesh dries and withers.][Thirty Years Old Stage: After 100 years, the blood runs dry and gives birth to mutations.]I am an Immortal Seeker, and also one seeking survival.

Thirty-three classmates hold a reunion after graduating. Tensions soar and old friendships are tested, as a strange turn of events lead them to follow the path of the ancient gods.