Fate's Slave - Shadow Slave X Honkai Star Rail - Chapter 25: Multiversal Manhunt

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.

I have calculated for people before I was born, and I have all five yin, and I am born with fierce ghosts. A knowledgeable gentleman said that I will not live to be seven years old. After death, I will cultivate blood-clothed little ghosts to harm people.

In order to save me, my grandmother married me a child-in-law, so that I had an Ann birthday, although I later discovered that the daughter-in-law and sister-in-law are not human…

I have been lingering and panting since I was a child, and I have been accustomed to accepting it, but my grandmother was killed.

For this reason, regardless of karma, I inherited my grandmother’s job of raising ghosts and vowed to send everyone who killed her to hell.

- Description from MTL

Instead of struggling meaninglessly, he acknowledged his place.

Countless dimensional worlds appeared, and human beings began to practice.

Open the gene lock, break the shackles of the human body, absorb the gene core of the alien animal, and extract the skills or talents in it.

Warrior, Mage, Archer, Assassin, Support.

“What is your job?”

Yuan Bei shivered while holding the self-made cheating system.

“I’m assisting, with hard control…”

This is the story of a hard-charging assistant spreading positive energy in the world.

- Description from novelbuddy