Skeleton Knight, in Another World - Chapter 15Volume 7 -

"I hope my wife liked the arrangements... for the wedding night."

[Ding! Congratulations to the host for obtaining the 9-Tailed Heavenly Demon Fox Bloodline.]The Celestial Fox Deity: “Little Ancestor, our geniuses are struggling to advance their bloodlines. Could you spare just a small drop of your diluted blood?”…Cain wakes up only to find himself transmigrated into a novel that he had read a few years before his death.In this new fantasy realm where the strong are respected and the weak are trampled, Cain awakens his “Unique SSS-Ranked Primordial Beast Master Talent” before an error happens and merged with “Extra’s Harem Gacha System” which can help him become stronger by having sex with powerful women, including those summoned from the system’s Summon Pool.[Ding! You have shared an intimate moment with the Goddess of Light][Ding! You have received …% of her stats attributes][Ding! You have increased her stats attributes by …%]After merging his talent with the system, he can also contract and evolve powerful beasts, instantly upgrading their ranks using Evolution Points.With the ability to convert money into Evolution Points, Cain decides to build his own force, amass wealth, and take full advantage of the system’s potential to rise above all.[Ding! Do you want to refine the Ice Dragon’s Evolution Pill?][Ding! Do you want to refine the medicine liquid of God's rank?][Ding! Do you want to refine the Godbreaker sword of the God’s rank?]…

Fifty years ago, the oxygen in the atmosphere changed, giving rise to a new form of air known as Spiritual Qi. Humans, plants, and animals alike suddenly awakened latent mutant genes and began evolving, gaining Superpowered Talents and Classes. Life took a new turn, and humanity had to adapt.Everything seemed to be going well until, fifty years later, a 16-year-old boy named Klaus awakened a terrifying Talent and Class. His awakening marked the beginning of a new era in human evolution.Unbeknownst to everyone, Klaus, who was shunned by society and dropped out of school to work for a better life for himself and his mother, was actually the last of the Nine Paragons—a being so powerful that even the heavens feared him.Watch as Klaus climbs the ladder of strength, pursuing absolute power with a single purpose: to protect and make his mother happy.

After the nuclear warfare, massacres started to spread throughout the entire world. The order between humans completely collapses, and the strong eats while the weak gets eaten becomes the #1 rule.