MTL - Rebirth Daughter Against the World - Chapter 6 Eating too many brain fragments?

Roy’s life was nothing special. The only thing commendable was the last few moments when he saved a mother and her child from a drunk driver.
…
It’s really an egg! Damn it, what kind of monster have I become? Did I fall into Hell instead of making it to Heaven??
Join Roy as he ventures through various worlds with the Custom Made Demon King System—a system that allows Roy to draw anything he can imagine and create it through exchanging souls!

The former Immortal Ascension Realm Cultivator Wang Che failed to overcome the Heavenly Tribulation, and as a result, his soul transmigrated to a world of the Martial Soul where soul beasts and humans lived together peacefully.

After hatching endless plots and suffering innumerable hardships, the demons of the Demonic Realm finally managed to resurrect the Ancient Demon King.

The demons of the Demonic Realm had hoped that the Ancient Demon King would not only lead them in waging a war against the Heavenly Realm and enable them to lord their superiority over the Immortals, he would also ultimately gain control over the entire realm.

Gradually, however, they discovered that their thoughts were very, very wrong.

Whilst it is true that this Ancient Demon King still retains his aura of superiority and possesses unlimited powers, he…

He seems to be a mental case…

It’s alright even if he changes orders and does things in an incomprehensible way.

But what’s with his habit of muttering under his breath, nagging and conversing with himself the entire day!

Small Orchid: He’s not ill, he’s just despicable (贱jian)…can’t stand to see (见jian) people live a good life.

Dong Fang: I am only unable to endure seeing you live a good life.

Small Orchid: …

*T/N: The Chinese pronunciation for the word “despicable” is the same as the word “see” – thus, the author is trying to show that Small Orchid, while trying to scold Dong Fang, is also careful not to incur his wrath, which is why she tried to imbue another meaning into her sentence after scolding him.

- 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.