Chrome Shelled Regios - Volume 20, Machinas Eye

An ordinary student accidentally traveled into an other universe and became the king of a small kingdom. He had gotten a “Cheating Code” of life and was able to complete something extraordinary. This is the story about a king that was able to conquer continents and leave behind him an ultimate legend that will be recited between every generation to come.

- Description from novelupdates

In the eyes of many people, Hefpaff College represents a mediocre idiot, while Slytherin is famous for its shrewdness, ambition, and sleekness.

When Hefpaff stayed with Slytherin, it was like a badger and a snake in the same room, and it seemed that badgers would always be bullied by snakes.

Compared with the dazzling other three hospitals, Hefpaff is mediocre, so many people forget Hefpaff’s academic spirit: integrity, loyalty, honesty, and fear of hardship. People who possess these qualities may not be in harmony with each other. Tom Riddle was equally famous, but their souls were stronger than him.

Professor Pomona Sprout from the valley is known for being good at the curse of food, and the gloomy and greasy Slytherin chief from the cellar often handles disgusting magic materials such as slugs. They don’t seem to have Any communication and scandal arise, but here is Hogwarts, what can’t happen even if there is magic?

Female lead text.

- Description from novelbuddy

“I don't share my possessions, Mr. Campbell. Your wife stole from me and now I want something back. You should know I always collect what I'm owed,”When Liam Campbell's wife steals from his wealthy female boss and disappears, he's left to face the music. But his boss, Lady Isabella Ashworth, has other plans for repayment—plans that involve keeping the handsome man for herself.Everyone thinks they know the score: young guy becomes a rich woman's plaything. What they don't know is that Liam's got more weapons than just his looks. Behind his perfect face lies a ruthless mind that turned him from a nobody into a rising star.Now, trapped in Isabella's world of luxury and power, he'll play her game—but by his rules. His main goal is to dominate her as much as she wants to dominate him.But who's really taming who?

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.