MTL - I, Luffy, Awaken the Sun God on the Top - Chapter 45

Jiang Chen, son of the Heavenly Emperor, unexpectedly reincarnated into the body of a despised young noble, thus embarking on the path of the underdog trouncing all commoners. No one has the right to call himself a genius in front of Jiang Chen, as no one has a better understanding of the heavens than the son of the Heavenly Emperor. “Genius? He who adheres to me shall ascend. Those who oppose me can find solace in hell!’

“Master, the people from the Zhuang family have come to cancel the engagement.”

“My fiancé whose beauty was said to be capable of causing the downfall of a city, finally decided to throw me away?”

“I think so.”

“I want to see this legendary beauty, and confirm whether this bastard is as really great as people said to have no flaws in all 360 degree, a picturesque appearance however you see him; does he need me to help him open the corner of his eyes (Epicanthoplasty) or reshape his chin (Genioplasty)?”

“Actually, he didn’t come.”

“He didn’t? He didn’t even come to cancel the engagement? What a wicked b***h.”

“He definitely will get karma.”

- Description from Novelupdates

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.