The Grandmaster Strategist - Volume 1, Chapter 5: Battle Over the Heir Apparent

While the demons were rising, mankind was about to become extinct. Six temples rose and protected the last territory of mankind.

A young boy joins the temple as a knight to save his mother. During his journey full of miracles and tricks in the world where temples and demons are antagonistic to each other, will he be able to ascend to the strongest knight and inherit the sealed divine throne?

- Description from novelupdates

Asura, a noble in the kingdom of Silvara, spent his days quietly until his world ended. Betrayed by his beloved wife and then killed, he swore to get revenge on them in his late moments. Upon death, Asura somehow returned 20 years into the past. Prepared to get revenge on the woman who betrayed him.On his journey for revenge, he discovers true love, friendship, and a life-altering truth.A dark cult controls his fate like a game—even his beloved's betrayal was their work. He learns about his powers and strange bloodlines. Then, about this being his ninth and final rebirth! All to revive their god, using Asura as the perfect vessel.Vowing to destroy the cult's plot and protect his loved ones, Asura forges an alternative path.Becoming the Devouring Monarch

This story is centered around the man named Yi Ji-Hyuk, who has spent 1000 years in a Medieval Western fantasy-like world before returning back to the modern-day Earth. When he returns, he finds that his home is facing monster threats, and that humans with superpowers have appeared to protect the innocent people of Earth.

The first part is finished, and the second part is starting. Two worlds of immortals and demons, and the boundless universe. This decides the tone of the second part!