You Practice Immortality, I Farm - Chapter 4: "Gengjin Sword Art"

Xia Yan passed through to the world of Bleach and became an eleven-year-old boy. He was rescued by Renji and Rukia in the Seireitei, and he was studying at Shin’ō Academy, and he was a student of the same class.
He is a top student of the Shin’ō Academy, and he is vying for strength by various teams. In the end, he has entered the first team of secret mobile maneuvers.
He will use punishment to kill every person who tries to threaten the martyrdom and protect his loved one.

- Description from Novelupdates

Zhou Heng thought the news of an impending solar flare and natural disasters was absurd—until he died in the apocalyptic chaos that followed. Reborn ten days before the end begins, Zhou Heng now knows the truth: earthquakes, tsunamis, plagues, and even zombies will devastate the Earth.Armed with the Doomsday Sanctuary System, he has a chance to rewrite his fate, but there’s a catch—it requires a shelter to activate.With only ten days left, can Zhou Heng gather the resources, fortify his sanctuary, and prepare for the storm of humanity’s collapse?

The dawn era after the end of the half century has gradually rebuilt the order, abandoned civilization, and is full of undivided violence and desire.
The noble and powerful pioneers are in charge of the city, and the evil and mad plagues are in the wilderness.
Pure human beings who cannot mutate are the weakest, dominated by the rulers of the pioneers, and are not as good as animals in the wilderness.
A purely humanized young man with a worldly experience has quietly entered the WTO, holding a three-foot long knife and a long-distance desire to boil in the world of purgatory. From the nameless name to the sorrow of the Supreme Court, the name of the black ride is resounding!

- Description from Uukanshu (translated)

With the revival of spiritual energy and the breakdown of the order of species, it is a difficult test whether human beings can still stand at the top of the biological chain.

(There is already an old book, The Strongest Descends in the City, you can read it.)

- Description from novelbuddy