Death March kara Hajimaru Isekai Kyusoukyoku (WN) - Book 17 - 17-12. Changing World

He, without doubt hates her.
What did she do to deserve his hate?
The person who she treated well like a brother did not even bother to notice it...

Years passed…

He needs to get married.
He needed a wife.
So she offered herself.
It was a marriage that will benefit both parties he said.

Morca, a mere mortal who dared to ascend to the heavens and claim his place among the so-called gods, ultimately failed. Not because of his own weakness, but because he was forced to watch his beloved little brother be slain by the Heavenly Titan Court’s envoy.In that moment of grief and distraction, the Heavenly Titan Court’s envoy, realizing they could not stop him through conventional means, placed upon him the Curse of Eternal Doom, a fate that ensured both the heavens and the abyssal realms would relentlessly pursue him until his existence was completely erased.And it nearly worked. His soul teetered on the brink of annihilation, moments away from being extracted.Then, everything turned blank.===Morca, after 'transmigrating' into the world of Eden, awakened a powerful system that granted him a unique SSS+ talent. This talent allowed him to grow stronger through battle and killing. With the system’s aid, he advanced rapidly, eventually ascending into the Oblivion Realm–a place beyond the known and the unknown. There, he uncovered a great secret that no one had ever imagined existed.During his journey to power, he met Neo Laura, a companion bound to him by the system.===The birth of the Child of Nihility. An entity destined to shake the heavens, the abyssal realms, and even the oblivion realm itself.===Everything in existence has an opposite. So, if nothing exists beyond the darkest space… then shouldn't its opposite be everything?Beyond the endless void outside the universe lies the Oblivion Realm, home of the Nihilians.They are described in a single word, Catalytic.They grow quickly. They Course destruction just as fast.Shrouded in mystery, their existence is a paradox.

Vergil, a 21-year-old young man, leads an apparently simple life in a somewhat troubled world. His family is also simple—although his father is no longer alive, his mother has always been by his side, despite being a bit... aggressive. But that's not so unusual nowadays, right?Everything changes drastically when Vergil, after an unexpected death, awakens as a demon. To his surprise, he discovers that he has accidentally married beautiful Pure-Blood demonesses.Now, he will discover how the world really works from a Demon's perspective.

This is an Isekai styled story, written from the point of view of the protagonist.

Discover the secret of the new, unknown world with Peter, as he sets his first steps in an empty, ruined city. Meet new people from all around the globe. Fight, laugh, and cry.