This is a world called Amaril. The technology has advanced so much that creatures, plainly called "beasts" were created. Although these "beasts" are anything, but plain.
They are capable of getting more powerful indefinitely. The beasts are born with a natural ability to cultivate and refine their bodies.
And so they had wiped out much more than half of the population, while the survivors built powerful defenses. That way the world was split into two sections: one for the humans and one for the beasts, which was exponential larger than the other.
But not all is as it seems, with the birth of "beasts" the first "Linkers" came into existence aswell. The possibility to create a soul-link with a newborn "beast" was discovered.
This soul-link allowed humans to ignore the limitations of strength, life expectancy and even gave them the possibility to use unique abilities that their soul beasts possessed and cultivated.
When the soul-link is complete the human gains the ability to see and feel the natural energy called "mana" and a vessel to store and use their mana, as they see fit. That is their soul beast.
The process of cultivation is quite simple, but arduous at the same time. With the help of the soul beasts, humans refine their bodies from inside-out, by gathering mana and refining each part of their body cell by cell and the higher the cultivation level, the more energy it requires.
And so the new type of humans called "Linkers" became the last hope of humanity. They strive for power, while cultivating their bodies with the help of their soul-beast partners. Our hero is Arthur. A youth of 15 years old. Today is the day he gets to link up with a beast of his own and set foot on the path of body refining.