Birth of the Demonic Sword - Chapter 2335. Branches

“Transmigrate as the Final Villain of the novel...” Ark stared at his reflection in the mirror he held. It was Theos Von Fallen, the final villain of his favorite novel.Although he was the final villain and the strongest in the novel, he was killed by the protagonist and his harem in the finale.[Ding. The Heroine Snatching System has started] Ark gave a crooked smile when he read the system message in front of him... “Exchange!” he shouted, unwilling to accept the fate they had in store for him.Trapped in the world of his favorite novel as the most “evil” and powerful villain, Ark, now Theos, will use his knowledge as a fan obsessed with the novel to take away all the protagonist's opportunities.Whether he can become the focus of the whole show or whether a script will dictate his fate, he will decide! He will live as a true villain who doesn't care about anything but his life and his loved ones.

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

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.