The Chronicles of a Lost Man in His Forties Founding a Nation ~Commonsense is Hindering Me From Becoming TUEE~

The protagonist is a former tabletop RPG fanatic who is now just a normal salaryman (single, male, 42 years old). He is sent to a parallel world by a mysterious entity.

The protagonist ends up living in the world ‘Sedia Continent’ as ‘Gio Margils,’ his max level wizard character from the classic tabletop RPG ‘Dungeons & Braves.’ While wavering between common sense and desire, the protagonist eventually becomes dragged into a war that will dictate the destiny of all humankind.