MTL - I Have a Sickness - Chapter 3 I have rabies

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.

One day, Luo Jian woke up from his sleep and found himself in a locked chamber where the door and window were all sealed. A note with a few lines written on it was tacked to the wall: “Escape from this room within an hour, otherwise, you will die.”

There is a sequel called Reincarnation Night (轮回之夜) that takes place in the same universe but has different main characters

- Description from Novelupdates

Hope Lauren has read her share of comics. She’s seen supers around her city and even been saved by some on occasion. And she always hoped that she’d be able to join them. With Jack, her grizzled older mentor with secrets that could shake the world, and Pantheon, a new team of heroes, Hope will have to fight against monumental odds to save Oleander City. In a world of action, comedy, tragedy, and adventure, there’s plenty for a new hero to do.*Readers can expect a mostly adventure-themed superhero journey that will include a slice of life, action, and hopefully exciting world-building. It will also contain a slow-burn GL/Yuri plotline, which I'll eventually get to when I feel like it, I guess. This will be a very long story with many arcs*

Born with the fate of a slaughterer, but all he wanted to do was help.