Kim Minjun, who was a normal high school senior in South Korea, was suddenly summoned to another world and became a dark magician. Minjun, who persevered through all sorts of hardships with the single-minded goal of returning home, saved this other world with his dark magic. Casting aside a life as a hero and guaranteed riches, he returned to Earth. Just when he was about to fully enjoy his life, a problem arose. A dungeon break occurred, and monsters began pouring out. Not only did this threaten the peaceful Earth life that Minjun had just returned to… But on his very first day back, he was also ordered to enlist in the military!?!