Eroge: I can Travel To The Ancient World - Chapter 4: First Villain Appears

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.

Zaiyila thought she had suffered enough—betrayed by her own mother and sold into marriage with a wealthy, aging man. But on the night of her pre-wedding ceremony, everything takes a dark and unexpected turn. A swarm of deadly snakes descends upon the gathering, killing her groom-to-be and throwing the hall into chaos. Fear spreads as the people recognize the serpents as the servants of the enigmatic and terrifying Snake King, Everett.When Everett himself arrives—a striking, horned man of unmatched beauty and power—Zaiyila finds herself drawn to him in ways she cannot explain. Despite the fear he inspires in others, she feels an unshakable connection to him, one that transcends the realm of logic. The moment she defies the fearful kneeling of the crowd, she unknowingly seals her fate.Taken into Everett’s domain, Zaiyila is forced to confront not only the dangerous, supernatural world she’s been thrust into but also the awakening desires she cannot deny. As she unravels the truth about her past and her connection to the Snake King, she must decide—will she resist the pull of destiny, or will she embrace the darkness and passion that Everett offers?A tale of betrayal, power, and an irresistible bond, Bride of the Serpent King explores the fine line between fear and desire, fate and choice.---

He had crossed into the dark, ruthless Wizard World.Lucien found his system somewhat different from the usual golden finger.System upgrade points? Chip activation?None of these, but rather becoming a role model, transforming into a nurturing breeze:Teaching students knowledge, receiving advanced knowledge in return.Caring for and maintaining students, earning generous rewards.[Your student has mastered the Magic Potion “Kuru's Cough,” congratulations on acquiring the improved formula “Kuru's Cough - Enhanced”!][Your student has mastered witchcraft “Fireball,” congratulations on learning witchcraft “Greater Fireball”!][Your student has successfully crafted the wizard's tool “Pale Mask,” congratulations on acquiring the wizard tool’s manual “Revised Pale Mask”!]Initially, Lucien was resistant.But after experiencing what it was like to teach disciples and outdo them, Lucien felt he had completely transformed into the form of the master system.This thing, isn't it much more useful than something called Cheating Device?