Start by Spending One Billion [Entertainment Industry] - Chapter 76

A data loving young man from Earth has an accident which transports him to a dark land filled with terrifying creatures and magical powers. Fortunately for him, he has a Biological Assistance Chip to ease his path. However, things in this bizarre and strange world are not always as they seem, and, though it is a tremendous asset, the chip doesn’t always work as expected. With all of the crazy creatures and magical mayhem around him, one can only wonder what the future holds for this young man…

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.

Time travelling from the majestic era after the Recuperation of Reiki, he became Kimura Kazuki, a 16-year-old high school student in Japan, one year before the Reiki Recuperation.

Tentatively, he set out to hone himself to the bone, burning candles at both ends to stockpile resources in preparation for the imminent Recuperation of Reiki. His goal was to be many steps ahead of all humanity when the time comes.

However, it seemed like fate had decided to play a cruel trick on him.

One year later, the Recuperation of Reiki… did not happen as expected.

- Description from Novelupdates

Killed On The Roof Top On Her Wedding Day By Her Just-Wedded-husband,Jasmine Trevor begged for a second chance at life.As If The Universe Heard Her Plea,Jasmine Trevor Was Reborn To Two Days Before Her Wedding With Jack Raven.This Life,She Vowed To Change Her Fate While Face Slapping Jack And Get A Sweet Revenge. What Would Be The Perfect Face-Slapping Than Getting Married To His Rival??Jasmine Went Ahead With The Wedding,on the aisle,she took everyone by surprise by introducing a new groom while she had security men throw Jack Out Of The Hall.A Villian Was Made. Getting Married To The Infamous Billionaire Monster Who Was Tagged As The Killer Of His Parents,Jasmine Was In For A Ride She Never Bargained For.Jasmine’s Taste For Revenge Made Her Get Entangled With The Sadistic Billionaire Who Has A Very Dark Past,One That Might Cloud Her….Thrust Into His Endless Abyss Through A Contract Marriage, Jasmine Was Stuck With Kingsley Elm—-Who Saw Her As His Possession. An Asset And His Obsession.“Be Tame,Little Vengeful Wife. You’re Mine Now.”