MTL - Worldly Stunning Blade - Chapter 9 Deliberate

In the year Stardate 1, mankind entered the interstellar age, with interstellar migration, spaceships, alien races, and outer gods...arriving one after another.By the year Stardate 717, Fang Xing looked out upon the cosmic backdrop teeming with dense armies of foreign races and declared that all aliens, cultivators, tentacles, esoteric teachings, and evil gods would be intimidated by his supreme talent and smashed to pieces with his iron fist...Well, this is actually the story of a transmigrator, who whimsically dominates many different worlds with the help of his professional panel...

Genius, antisocial, solitary, intractable , maniacal.

At the turn of every era, it is he who raises the flag of the rebel cross.

Winners take it all, losers take the fall.

He who brings order to a chaotic world, assembles talents and masterminds.

He who hides among the crowd, yet stands on the top of the world.

— The one and only, him.

- Description from Novelupdates

...[Inside an underground basement]“You are going to die for nothing, hahahaha,” the old man's voice thundered through the room, sending chills down my spine.Step.With a swift and ruthless motion, he lunged forward, his sword slicing through the air and slashing my throat, crimson droplets staining the darkness.“We'll see,” I whispered defiantly, my final words escaping as a mere breath against the impending darkness.Slowly, inexorably, my consciousness slipped away, and I descended into a deep, unfathomable slumber.“Huh!?” My eyes fluttered open, and I found myself seated in a bustling tavern, the air thick with laughter and the clinking of glasses.In front of me stood a captivating lady, her beauty juxtaposed with an angry furrow upon her brow, threatening to shatter the harmony of the jovial scene.“Don't follow me around!” Her words pierced the air like shards of ice, the intensity of her emotions palpable as she cast a resentful glare in my direction, before swiftly departing from the tavern....Am I trapped within the confines of a game? The fragments of my shattered common sense scattered before me, leaving me to question the very fabric of my reality.

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.