Naruto: I Have a Gravity Training Room - Chapter 39

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

Xiao Ze, who was dedicated to the people and vowed to become a generation of Ming Jun, accidentally fell on a little lady.
The little lady was born beautiful and lovable.
So Xiao Ze accepted his life and got the name of fear.

ps:
①The male protagonist has no concubine, and he is dedicated to serving the country.

- Description from novelbuddy

Qin Yichen returned to his youth with his memories of more than 10,000 years. Superb mental strength, advanced elixir formula, advanced martial arts.

- Description from xbiquge

He shattered the heavens… and got isekai’d into a crazy desert survival game!Xu Tao cultivated for ten thousand years, defying death and destiny to reach the Divine Heaven Immortal Stage.But just as he touched the heavens—The heavens kicked him into a world based on a full-dive VR game.Now he’s got no Qi. No weapons, no cultivation… and no pants.Just a desert full of monsters, a glitchy “Lost System” that won’t shut up, and knowledge forged from millennia of clawing his way to the top.Enemies? Weaklings.Mystic beasts? Drop garbage loot.Level caps? He’s Xu Tao.He didn’t spend ten millennia chasing immortality just to get wiped by a scorpion in a tutorial-zone!But he’s definitely not here to play. He’s here to ascend—again.Even if this time, he has to grind EXP and punch sand beetles to do it.But wait... That's not all...? He could also... What?!