MTL - Monster Paradise - Chapter 1870 cool!

A skilled but unfortunate modern-day assassin was killed in a freak accident. However, he soon found himself summoned to another world by an evil wizard, who had him possess the body of a boy as an experiment. After successfully planning the evil wizard’s downfall, he used the wizard’s body as a springboard to gain influence and power in his new world.

- Description from Novelupdates

Years ago, Earth was indoctrinated into the “System.”Earth was not the only place with the System, however. With the System came the other races, Invaders. The Invaders had one goal, to obtain ownership of this new habitable planet. This created a bloodbath, and for years the war raged.This didn't really have much to do with Derek. Derek was kind of a loner. Yeah, he enjoyed the occasional chat or drink with others, but he never stayed in one place too long or really got to know anybody new.Derek did happen to be rather strong. After the years of fighting monster and Invaders alone, he had become quite adept at surviving. One thing that helped keep him alive was his refusal to get involved with others. He rarely cooperated with teams.One day, Derek broke his rules and decided to lend some help, as the mission didn't seem too hard. He should have stuck to being alone.

For the wine to be drunk on her wedding night to actually have been a cup of poison and for the one to poison her to be her husband, who would believe it?

Bro, I mean, I'm just a tad handsome, a bit skillful, and slightly crafty, that's all! Why do you all have to make my life difficult? This incessant pestering isn't the answer, is it?What? You'll marry no one else but me? No...you...how could you? Without even asking for my consent?