Toaru Majutsu no Index: New Testament - Volume 16, Chapter 3: Mutual Request for Assistance between Enemies - Double_Enemy.

The mid-level boss of my company’s AAA-game.

Frascoia Continent… Various races like Celestials, Demons, Humans, Monsters, Elves, Dwarves, and so on occupied this continent.

Humans and the other races lived on the mainland of the continent while the Celestials and Demons lived in Heaven and Purgatory, respectively.

Within the Demons, a prodigy named Azaroth rose quickly, even by demons' standards, to the point of being dubbed a Demon God. There was only one person above him within the demons: The Great Demon Venerable, the Demons' Supreme Godfather.

Azaroth's extraordinary talent never had the chance to blossom to its full potential; a terrible calamity struck him down and he died soon after. But was this calamity just misfortune or was it hiding an opportunity for him?

Near his deathbed, he prepared for his future ascent to achieve his lofty goal.

Millions of years had passed after Demon God Azaroth's demise and now a young aristocrat called Edwin Rhodes came across a mysterious cave.

Today, I am a substitute for your fiancee. Tomorrow, I’ll become your sister-in-law!

Mu Mingtang is the substitute of the male lead’s first love. After she lost her family, she was adopted by the Jiang family and eventually became engaged to the male lead, the Prince of Jin.

Understanding very well that she was only a substitute, she removed her claws and fangs and turned herself into an imitation of the Prince of Jin’s first love. She couldn’t speak or laugh as she wished, she was prepared to live in the shadow of another woman for her entire life… until one day, the real Miss Jiang returned.

The real Miss Jiang was reborn. When she learned that she was the male love’s first love, she immediately returned to fight for her engagement and identity.

In order to please his first love, the Prince of Jin gave the substitute to the Prince of Qiyang, who had become a dying madman. She was just a low-quality fake, anyway. If she dared to anger his first love, he would turn her into a childless and powerless widow for the rest of her life.

Mu Mingtang, the target of their mockery, finally snapped: Okay, since you gave me to another man, I’ll make you bow and call me sister-in-law!

However, none of them expected the Prince of Qiyang, the God of War, to actually wake up!

—

Xie Xuanchen is the son of the late emperor. The whole world once trembled beneath his feet, but one day, for a reason unknown to even Xie Xuanchen himself, his nature suddenly changed. He became cruel and bloodthirsty, leaving his father with no choice but to pass the throne to his uncle.

Eventually, Xie Xuanchen was unable to resist the illness and fell into a coma.

When he woke up again, there was a beauty standing before his bed, looking at him in surprise. Then, for the sake of his domineering little princess, he revived his name as the God of War, reclaimed the throne, and united the world.

I once captured the world to satisfy my own ambition. Now, you are the reason for my ambition.

Yun’s once-famous disciple Yun Yun, entered the family ancestral hall and became a living dead.

After two years of sleep, the protagonist is strong and awakened.
Among the Tianzhu Taoist tombs, the Tenth Heaven Emperor passed down.
Seeing that my body inflammation is swallowing fire, the ten gods are floating!

(Level: Wuren, Wushu, Dawu Division, Lingwu Division, Wujun, Wuwang, Wuzun, Wusheng, Wudi, Wushen)

- Description from 69shu (translated)