Star Wall: The Age of Counterattack

The story follows a former frontline cannon-fodder squad leader who was surrounded and killed while fighting the extraterrestrial demon race. He returns to thirty years in the past, with the demons due to descend in thirty years. In this life, he must lead the whole territory to prosperity, develop technology, teach martial arts, and simulate battles against the demons, preparing to wipe them out once and for all when they arrive!