Isekai Douraku ni Akitara

An unremarkable thirty-something man spends his days buried in work, with barely a moment to himself. When things finally settle down and he gets his first real break in ages, he decides it might be time to find something new to enjoy. “Traveling sounds nice, for example.” As if the universe heard him, his journey begins sooner than expected. On his way home, he suddenly finds himself stranded in another world—a strange, game-like place governed by levels, magic, skills, and other fantastical rules. And before he knows it, he's acquired tremendous power without even having to work for it. With that kind of strength at his disposal, three paths lie before him: side with humanity and become a hero, join the demons and unleash chaos upon the world… or choose neither and use his newfound power for nothing more than his own amusement. For him, the choice is obvious. And so begins one thirty-something nobody's journey through another world, living exactly as he pleases until he gets bored!(Source: Hanashi Media)