MTL - I Wield a Sword at Hogwarts - Chapter 61

The young lord of a small and weak country saves a dragon beside the sea one day.

Xia Zhijun got the title ‘study god’ after scoring first place in the whole city. He’s the model of a good student in a teacher’s eyes: good grades, good manners, and quiet. When he wasn’t smiling, his entire body emits a cold abstinence aura. The girls only have the guts to look from afar and not get close.
Later, it was rumored throughout the entire school that even the study god would fight and hit on girls. Whoever dared to provoke his girl, he would teach you how to be a person at every minute. The night of the graduation ceremony someone saw him blocking Gu Siyi in the corner. He didn’t stop kissing even when she cried. He bit her lips and said in a raspy voice, “I’m going crazy…”
During college finals, Gu Siyi almost bursted out crying, “I’m such a failure. I won’t be able to find a good job in the future…And if I can’t find a good job, I can’t provide for myself…”
Xia Zhijun played with her pink earlobe and remarked, “I’ll take care of you.”
After they graduated, Xia Zhijun created a research company and Gu Siyi became the boss’s wife.
The commercial rocket, “Star of Siyi” was successfully launched. So everyone knew that the new technology superstar, Xia Zhijun has a wife who he spoils a lot.

- Description from Novelupdates

Thrust into an enigmatic world born from bloodshed; venture inside its complexities, dark-side, and always changing nature. At the center, a boy; brought up by an exiled mage, steps into a life of independence. A test to try and change his life for the better after witnessing what war can do to a person. The walk towards finding a stable living gets toppled as a unique magical element awakens. Using people, toying with emotions, doing anything and everything to get what he wants, this is the life of the next Death Reaper. Mostly emotionless, life continues as questions about his state of mind and being remains clouded behind many personas.

This isn’t the story of a single man, it’s the story of a whole world. Read as the world builds itself from the ground up. Conspiracies, evil, the dark side of humanity. In addition, tis the start of a new age; the birth of monsters – a story depicting the tales of the first heroes and demons to ever exist.

The Wielder of Death Magic isn’t a typical fantasy. The heroes don’t summon forth power from heroes of old, here, the characters are the ones who make up the myths and legends for the next generation. Amidst the turmoil, Staxius, he lives on, watching and waiting as the world grows.

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.