Transcended as Lord Buggy - Chapter 12: Hunting 50 Millions Crew

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

- Description from Novelupdates

Yo, Hi! I’m Frank, I made a deal with a demon to pay me some money for receiving a guest for a few days every week.
I had no idea about what I have done.
On May 1st, Conan ‘the God of Death’ came to my house. I was forced to let him in and we get involved in a criminal case.
On May 8th, Bruce Wayne ‘Batman’ came to me. I was forced to follow him to fight crime.
On May 16th, Hannibal Lecter, The Silence of the Lambs, came to my home. I can only say that I really can’t stand my guests.

- Description from Novelupdates

In this school fantasy story set in the distant future, creatures contaminated by pollution have overtaken the land, forcing humanity to live in isolated mobile cities called Regios. One such city named Zuellni is a self-contained school in which freshman Layfon Alseif has just enrolled. Layfon reluctantly joins the 17th Military Arts Platoon led by the third-year student Nina Antalk and embarks on a series of adventures.

Time travelling from the majestic era after the Recuperation of Reiki, he became Kimura Kazuki, a 16-year-old high school student in Japan, one year before the Reiki Recuperation.

Tentatively, he set out to hone himself to the bone, burning candles at both ends to stockpile resources in preparation for the imminent Recuperation of Reiki. His goal was to be many steps ahead of all humanity when the time comes.

However, it seemed like fate had decided to play a cruel trick on him.

One year later, the Recuperation of Reiki… did not happen as expected.