An ordinary person unexpectedly unlocks a cross-era Sky Screen System, capable of projecting complete historical footage from future generations into the timelines of every dynasty. Emperors and civil and military officials throughout history watch the rise and fall of a thousand years unfold simultaneously, from prosperous golden ages to the disasters of war. They witness firsthand the past deeds of treacherous officials who brought ruin to their nations and loyal ministers who suffered wrongful accusations, learning the ultimate outcomes of various historical events. Many rulers are filled with regret and send invitations across time to virtuous ministers renowned throughout history, hoping to bring them to their own kingdoms to offer guidance. They also use history as a mirror to reconsider their successes and failures in governing their countries.