Bog Standard Isekai - Chapter 38Book 3.

A girl who calls herself a demon appeared before a timid student named Fumio Kijima. The girl claims to be a campaign girl from the demon world and she gives him the ability to “summon a room” from nothing but thin air.

At first he doesn’t abuse his power and uses it as a convenient ability in his every day life. But one day he is bullied by his classmates under a false pretext and is made to suffer. In the past he would have wallowed in misery and cried himself to sleep, but now he had a power to call upon.

“I will make them regret it!”

Using his powers to summon his “room”, he begins his era of confinement and brainwashing to achieve his goals.

In his first life, Victor was lazy, poor, and the ultimate gambler, but the Goddess of Envy gave him a chance.

[ Die and go back four years into the past to restart your life. ]

Victor lost all hope and killed himself, and so began his second and also the most miserable life.

He became rich and successful but soon his girlfriend betrayed him and took away all his fortune, having decided on a desperate act Victor came up with a plan to avenge himself.

Although his plan was successfully executed, Victor hoped that this time he would die once for all and forget the despair that followed him through his two lifetimes.

Yet as if to deny him of his salvation, he suddenly heard a feminine voice once again, but a different one this time.

[ Goddess of Lust, surprised by your actions, grants you a gift ]

[ Yandere system activated! ]

It was a turning point for Victor.

From now on whether it is a Goddess, a Vampire or a Succubus, no matter who it is I must seduce you or I will surely die this time!

Torn apart and eaten alive by zombies, Jiao Lizhi died filled with regret and hatred. As darkness engulfed her, she opened her eyes—only to find herself back at the beginning of the apocalypse. Crawling back from hell, she sought revenge and fought to live a better life.Watching his loved one torn to pieces before his eyes, he lost his sanity. To avenge her, he destroyed humanity’s last hope with his own hands. On the day the world was swallowed by darkness, he took his own life as the last man standing on Earth. When he opened his eyes again, he vowed never to lose her again!As the world turns into a living hell, will they be able to undo the regrets of their past lives?TRIGGER WARNING!Gore, Violence, Graphic scenes, Abuse.

He rose from abjection and achieved eternity in glory.
He embraced the prettiest beauties and killed the strongest opponents.
He was able to shift the clouds into rain and cover the sky with one hand.
He could overrun the entire world and go anywhere as he pleased.
He pacified wars and held the world in awe.
He was matchless in the world.
However, his hair turned white overnight for his beloved woman and he was on the verge of death.
He was surrounded by enemies who were trying to take his life.
He struggled his way to become mighty and fought for everything he cherished.
For this age, he was the only king of the Dark World.
His name was a byword for might.
As a man living in the world, his only ideal was to pursue brilliance.

- Description from Novelupdates