SSS Ranked Shadow Monarch: Summoning Infinite Shadows - Chapter 26: Scouting the caves part 1

She is the twenty-fourth century’s strongest immortal cultivator, but transferred into a world of magic where demons roamed rampant; a punching bag tyrannized and ostracized by her clan on one side while the scum of a man that is her fiancé humiliated, trampled her on the other side…

The rivers and lakes carry wine with swords, the waist is slender and the palm is light.

The young man carried a long knife on his shoulder, and hung wine on his waist, striding forward, but the rivers and lakes in his heart were vaguely visible.

Turning a page in the book of troubled times, the rivers and lakes have been raining nightly for decades.

Looking back suddenly, the world has been shattered.

- Description from novelbuddy

Xueyue's life was filled with nothing but unfortunate events. Her mother died giving birth to her, her father abandoned her for another family, her stepsister stole her beloved, and she was framed for a murder she didn't commit.
Sentenced to death by beating, Xueyue thought her horrible life would finally end.

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.