Zero no Tsukaima - Volume 16 Chapter 9

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

This red dragon came from the vast wilderness, coveting all the powers of the world. He has held countless titles: Mountain Fury, Purgatorial Calamity, Red Emperor, Ember Dragon…The world trembles under the shadow of the great dragon. He ignited the surge of the magical industrial revolution. In the empire he established, wyverns roar, cannon fire resounds, steel behemoths appear in the sky and on the earth, and disasters from other worlds run rampant.“Submit, or die.”Cassius spread his sky-shading wings, looking down upon the trembling humans, elves, and dwarves beneath him, and spoke thus.………A story of a red dragon with a built-in player template conquering, ruling, and transforming another world.(Pseudo D&D, Fourth Catastrophe, Red Dragon, translation )

Rein Aster was just a herbalist farmer from a border village.A nobody. A background NPC in a story filled with prophecy and divine warfare.But by chance—or fate—he saves one of the 7 Demon Lords during a catastrophic war event. Instead of killing him, she falls for him.Obsessively. Violently. Eternally.And then… so do the others.Each Demon Lord tries to trap Rein as her personal lover/pet/priest/husband/god, building dungeons, illusion palaces, soul prisons—but Rein keeps escaping. Quietly. Cleverly. Never fully rejecting them—but never submitting, either.Why?Because Rein realizes something:The gods are worse than demons.The heroes are tyrants in shining armor.The world is collapsing—and he’s the only one they all listen to.So he hatches a plan:Use the Demon Lords’ love to take over the world.Pit them against the heroes. Unleash them on the gods. Make them fight for him. Make them kill for him. Then tame them all.Not as a king.Not as a savior.But as the lover they would burn the world for.__________The yanderes here are darker than what you might be used to.You have been warnedThe entire novel has a dark feel. Atleast read the first two minor arcs

The Capital’s girls look on with hatred, “ You’re just a country girl without any knowledge. Do you have Niyun Shop’s clothes? Do you have Brilliant Treasure Pavillion’s jewellery? Do you even know how eminent and domineering the famous Yue Wang is?

Mu Yunyao looked at them lazily, “ Niyun Shop? I opened it. Brilliant Treasure Pavillion? I opened it. As for Yue Wang…when are you returning my silver?”

Yue Wang’s face was cold: “I will pay with my body.”

(Wang means King. In this case, “Yue Wang” was a title given by the Emperor to his son.)

After being reincarnated, Mu Yunyao believes in three things: One, do not have good intentions towards others. Two, do not let the enemy have the chance to rise again. Three, do not believe in feelings. Thus, she is merciless. She is fearless. She would rather have everything destroyed than to compromise for everything.

However, after one fateful meeting, a cold-blooded prince keeps following her, silently plotting on making her his wife and bringing her back to pamper her…

- Description from Novelupdates