Reborn in Naruto As Madara's Grandson - Chapter 555: 520. Kabuto’s True Power

Within the Immortal Realm, there were nine thousand major realms, with three thousand at the top, three thousand in the middle, and three thousand at the bottom, along with countless minor realms.

A novel revolving around being transported to another world with an op system. The mc spends his day chasing skirts and doing missions to level up. A standard journey to the top with lots of girls from various animes and games with a twist of that gaming feel (hunting mobs, doing missions).

Freak Xie Ao Yu originally had no way of cultivating battle qi but, by accident, he got a mysterious godly pellet and he received a supreme emperor blade. That changed his destiny and from then on, he felt the real meaning of life and he made original time and space related battle skills and decisively battled ancient, huge clans and hundreds of continental clans in the Qi Ao continent.

Clouds formed with a flip of a hand and rain formed with another flip. He left the strongest mark in tens of thousands of years of history and created glorious chapters about a tyrant’s anger, blood shed for thousands of miles, the skies hissing from mad blades, and the allegiance acknowledgement of all times.

- 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.