This description makes a bit more sense.
In ancient times, Emperor Gu Ta Sian restored peace in the Tian Yun empire by defeating the dragon king Duang Tong Tian. Now, the seat of the king is open for a new prince.
Royal blood, Gu Chen Sa, has never been interested in being king, thus goofing-off in his studies. As the 19th in line, he has plenty of older siblings more worthy, smart, and hardworking than him. Neglecting his royal privileges, Gu Chen Sa can't escape the bad treatment he gets around the palace. Yet deep down, he admits his own irresponsibility.
But after discovering a dusty lacquer box in the royal library, Gu Chen Sa's view of taking an emperor's role suddenly changes.