I am that male friend in the harem story - Chapter 179: Pretender

An ordinary sect cultivator, with the help of the immortal mansion, gradually grew up in the cruel world of immortality, and his mind and body transformed together.

Mortal flow, partial dark wind.

- Description from novelbuddy

Chang An, capital of Tang, the most powerful empire in the continent. A heaven wrecking massacre shook the city to its core. Amidst the incident, a young boy named Ning Que managed to get away, dug out from a pile of corpses along with a little girl called Sang Sang. Years passed, and since that day the two of them lived together. Together with Sang Sang they both entered the military, with plausible military achievements, they were recommended into the Scholar School, which began their miraculous journey.

After breaking up with his girlfriend, he accidentally acquired a genius system and rose from there against the heavens, becoming invincible..

- Description from Novelupdates

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