Campione Scumbag in Mash-up Anime - Chapter 17: Pandora

Zhang Ruo Chen was the sole male heir of one of the nine emperors of the Kunlun Field. Ruo Chen’s father was known to all as the “Enlightened Emperor”, however Ruo Chen didn’t just leech off his status as emperor’s son. He proved himself to be a dragon amongst men, possessing a heaven defying body, and managing to cultivate to Greater Perfection within the Yellow Horizon Realm, at just the young age of 16.

But even though he stood at the summit of the younger generation and had a boundless future, he sadly died at the treacherous hands of his own fiancee at a young age.

Reincarnated 800 years later in the body of a young boy who shares his name, he found out his former fiancee already unified Kunlun’s Field and built the First Central Empire, and was now known as Empress Chi Yao… Empress Chi Yao—Her Majesty governed the mortal world and enjoyed prestige in all directions as well as an eternal life.

Zhang Ruochen stood outside of the Imperial Ancestral Temple, looking at the statue of Empress Chi Yao, and the flames of hatred burned in his heart. “After I practice for 13 years, I shall send the empress to her doom!”

- Description from Novelupdates

A rookie clerk asked his senior curiously: I heard our President is already married?

On her wedding day, she was humiliated; her status as the legitimate wife was instantly changed into that of a concubine.

“wh***! Marrying you is my life’s shame!” These were the hurtful words that came from her childhood sweetheart, now husband.

….

Jiejie, jiejie, thank you for your sacrifice. Jiejie, if you’re kind then go. Meimei will replace you and take good care of your husband, to help you enjoy the blessings that you are unable to enjoy!” these words spat out by her smiling cousin made her whole body feel cold.

….

“You are shameless! There is no need to say anything! From now on, our Shen family will not have you as our daughter! Someone! Throw out this shameless woman!” These were her relatives?

…

Becoming the target of criticisms, and being submerged in a small lake, she realized that all of this was the result of another person’s scheme – but it was already too late!

…

Instead of dying, she went back to the past, back to where both feelings were still alive and were loving towards each other; back to when she was not yet an orphan but the doted on Di daughter of the Shen family.

No matter what, in this life, she would never allow anyone to hurt the people she loved. And those people who harmed her in the previous life, she would make them pay the price!

- Description from Novelupdates

The story is about a a hitman, Who dies because of his own recklessness and transmigrates into a game he used to play after his retirement as a hitman.I'm not gonna spoil any further, but i might answer few of your questions.Is MC overpowered?Nope, he'll become strong over time and all battle he'll fight will be because of his effort and techniques.Is there magic and adventure?Yes! It have both magic like normal isekai with adventure and fighting with monsters and many other things. There are other important things like “Essence Stone” But let's talk about it in the chapters.There will be harem?Not really, He will be in contact with many beautiful female and males but one waifu but i haven't decided yet.All i can say is, give it a try, I'll try my best to make it worth your time.