Synopsis

A fractured modern world where a previously sealed breach in time-space allowed the flow of a new type of energy known as Miasma. The Miasma completely engulfed an entire continent, transforming it into a wasteland inhabited by monsters and natural disasters. These monsters were either created by the new environment or by once-peaceful species that have since become corrupted and evil under its influence.
Super humans and creatures resembling demi-gods began to appear along with the rift.
In this universe, the main character, a soldier with no discernible ability, is summoned twice after his initial run resulted in the destruction of the world. After his first run in this world failed in complete destruction, he promised to no longer play the hero and focus on what he can do.
He would help humanity through the shadows so that his presence would be known as little as possible, and he would let the heroes suffer so they may get stronger. He will quietly infiltrate those who want to end the planet and incite them to battle.
Mercy, cockiness, and foolishness are no longer present. He will be sure to take the Butterfly-effect seriously this time and put all of his efforts into protecting humanity, even if it means losing another friend.