Enki and King En were both taikis who originated in The Twelve Kingdoms, but were born in Japan. Enki was found by his nyokai when he was left by his parents in order to preserve their health. The nyokais of Mt. Hou treated Enki with the utmost care, and when the time came, he had to choose a ruler for the kingdom of En. Though there was too much pressure burdening his shoulders, and created a shoku to escape to Japan. There, he met the future King of En. In Japan, he was the leader of a clan, and was respected by everyone. He created a plan that would save all the villagers, but they all stuck by him, but were killed in the process. Only Enki and King En were left. Enki declared him king.
This was a really good background story to two people. It's rare that an episode is able to tell an excellent tale for two characters in just one episode. Though in here, even though their minutes were shared, the pasts of Enki and King En were quite great. How King En led his clan was something unique. It's kind of hard to explain, but what I do know is that it was extremely entertaining. Enki's part of the story was good, but not as great as King En's. Still, many animes out there could take some notes, maybe even thick books worth of notes, and learn how great character development episodes are done.