Naruto: The Outsider's Resolve - Chapter 1.5 (015):

Life is unpredictable. Her husband loved her stepsister, deposed her as Empress and even forced her son to death. In that Cold Palace, she was forced to drink poisonous wine. So in the next lifetime, she made a promise to never do good deeds and help others, to never step into the palace and to never become the Empress!

Year 2035. The virtual reality game, Warlord, changed the world. An Jaehyun was one of the many who wished to change his life through the game. After dedicating his life to the game, he was met with a betrayal. A betrayal by his comrades. As a result, he lost everything. But a chance was given to him. A chance to redo everything again! “I won’t play with others ever again. Whatever the outcome, I’ll show that I can do it alone.” Others rolled a dice to split the spoils of victory. An Jaehyun ate it all by himself. It was the start of An Jaehyun’s solo game life.

The heavenly God of Warriors was betrayed by his true love and murdered at the very first night of wedding just because his merits made the monarch insecure. Reborn in a hundred years, Nie Tian would be an appendage no more. Reach the welkin, reverse the fate, reign over the heaven and reconstruct the worlds.

- 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.