Taming Beasts to Survive: I Can See the Prompts - Chapter 12

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

A novel revolving around being transported to another world with an op system. The mc spends his day chasing skirts and doing missions to level up. A standard journey to the top with lots of girls from various animes and games with a twist of that gaming feel (hunting mobs, doing missions).

“With my knowledge, give me a fulcrum on which to place it and I shall move the world!”

…

Sorcerer Continent—a world where sorcerers exist. Wielders of arcane knowledge. Masters of all elements. Sovereigns of space and time. These sorcerers governed the world with their unrivalled prowess. One day, a young man awakened into this world with his past forgotten and no place to call home. Follow along as Glenn, by relying on his luck and wit, tries to survive and advance in this unforgiving world. Entangled within the machinations of fate, political schemes, power struggles and wars, he forges his own path and creates a place for himself.

- Description from Novelupdates

Mason was a mercenary, until the day he died on a mission after being betrayed by his unit.