Martial King's Retired Life - Chapter 48Book 15:

A lifetime ago, Chu Xun was shackled and thrown in jail on false charges. For three whole years, he suffered extraodinary torment from his cellmates every day. Even though he had escaped death many times, he still died from his cellmates’ fists the day before he was to be released.

After death, Chu Xun transmigrated to a different world of cultivation, where cultivation was the one true path. Carrying the weight of his hatred, Chu Xun began to cultivate in hopes of becoming an Immortal Emperor, who could manipulate heaven and earth and travel through time. After painstaking cultivation of three thousand years, he succeeded. Then he sacrificed all his cultivation without hesitation and returned to the day before he was to be released.

This life, he wanted to find out the truth and the one behind his murder in last life. He would continue to cultivate and strengthen himself so that the tragedy would not repeat itself. He wanted to master his own destiny.

In this life, what people would Chu Xun encounter and what experience of love and hate would he have with them? What difficulties would he encounter and how would he overcome? The answer is the book.

Legend says, that there is a great demon, who is the human kind’s public enemy. He is the galaxy federations’ nightmare as he wanted to conquer the whole universe. On the first day, he completely took out the human fleet, plunging them into disorder. On the second day, he declared that he will wipe out the whole federation. On the third day, he declared——that the hero who shot him in their previous battle must marry him, or else, he will destroy everything.

The galaxy federation president and the council members had a long meeting after that. They decided to dispatch a soldier, Wu Xing Yun, and marries him off to the arrogant demon. Wu Xing Yun was once a hero who fought for the nebula, and henceforth, he was tasked—— for the sake human race and the universe’s peace, to eliminate mistresses, settle his matters with the mother-in-law, and fix the man’s crooked ways.

Wu Xing Yun was very perplexed when he asked his commanding officer: “Sir, why did it have to be this way?”

Commanding Officer: “Soldier, bear in mind, that this mission of yours, is for the sake of the universe and mankind’s happiness. You must hold on to your husband, and fight other mistresses! Do you have the confidence to accomplish this task?”

Wu Xing Yun, stood straight, saluted, and instinctively replied: “Sir, yes sir! I will accomplish this task!”

- Description from Novelupdates

5 years after the world changed, the final boss appeared.

After the death of her grandfather, Lu Xiaoxiao, a girl who lived in the 23rd century, lived alone in the villa left by her grandfather regardless of the dislike of relatives.

Suddenly, she found that her grandfather left her a space in Yu Peili. She likes to read novels, fearing that the end of the world will come, and she starts hoarding things desperately.

In the country, it became the body of an 8-year-old girl named Lu Xiaoxiao whose parents both died with the same name and surname. Fortunately, the space has come together, even in this strange era, I can live well

- Description from novelbuddy