Never Marry a Man With Two Tintins - Chapter 33

Fate, a gatekeeper who had been working for the castle, is beset by a few burdens.

Su Xin was a world-class hitman. One day, she died in a disaster and was bound to the Fate Trading System to change other people’s destiny and increase her own life span.

Brothel prostitute: I want to become the first beauty of the Four Countries!

Imprisoned Mermaid: I want to return to the deep sea and become queen!

Adorable Loli: My elder sister is not human, kill her!

Miss Republic of China: Don’t let older brother be extremely infatuated with third aunt!

Su Xin: Your circle is really messy…

- Description from Novelupdates

Death is sometimes not the end!
Dead prison!
This is a magical prison. It has the ability to draw the souls of the dead people of the world, and it also enables people to gain the ability of the souls of the dead.
When Qin Song woke up, he was shocked to find that he had come to the world of One Piece, and even more surprised that he found a prison in his body…..

- Description from Uukanshu

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.