The Guide is Actually a Body-Switching Esper [BL] - Chapter 5: The Union

Lucas was the last human in the universe.A cosmic-scale war had consumed humanity in massive destruction. As collateral damage, there were no longer any habitable planets. Lucas Alhamera, a scientist, attempted to terraform a planet resembling Earth called Antroseda but continuously failed.Overwhelmed by despair and the crushing weight of loneliness, Lucas attempted to end his own life using a euthanasia capsule. However, just before his life could be taken, he was abruptly awakened by a notification.[As the last of the dominant species, you have been chosen as the new Overseer of this universe.][The cycle of life must continue to preserve balance.][Select planet as the birthplace of the new species (default)][Select another planet...]With the Overseer System he had obtained, Lucas began what he had failed to do for hundreds of years: reviving a dead planet and creating a new race to succeed humanity.

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.

Apocalypse befell, and roommates performed a skyward ritual.As the fog descended, the Book of Blood Spirit appeared in the hands of all survivors, and only those with a Contract monster could survive.Su Han directed his gaze to the neighbor who had already mutated and twisted, silently pulling out a gleaming fruit knife...Grotesque meat corpses, giant spiders with gaping mouths, eyeballs enveloping the city, one-eyed sharp-toothed hand monsters...Civilization fell, cities shattered, and all humans became meat for the monsters. There was only one way to survive:Use monsters to fight monsters.