Reverend Ecstasy - Chapter 46: Mutiny

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.

Ling Xiao was a powerful martial expert who fell in battle and was unexpectedly transmigrated into another world. He began life anew in the body of a boy with the same name, a fallen genius of the Ling Family whose cultivation had been crippled in a surprise attack, and son to a father who had also suspiciously been crippled under similar circumstances. Armed with knowledge from his previous life, Ling Xiao aim to restore his strength and establish his place at the top of this new world

- Description from Novelupdates

The leader of the thousand demons, the Demon God Chun YeoWoon. Due to an unfortunate accident, he had been sent to the distant future.