So this weeks myth actually exist in many cultures, and is most likely more in Chinese Mythology then it is in Korean, but I included it as Korean because I found it while searching for Korean Mythology. Do not get me wrong though, it is found in Korean myths, it is just more prevalent in Chinese. So all the names are in Korean.
The Dragon Kings of the Four Seas are kings of underwater sea palaces that correspond with the four cardinal directions. During droughts and floods local gentry and government officials led the communities in different sacrifices and religious rites so as to appease the dragons. There are actually more than four, but these particular four are the highest status of Dragon Kings. In Chinese mythology, they are celebrated as deities of the sea like Mazu. But unlike her, they wreak havoc, and she is protective.
One particular year, the Dragon King of the East and the Dragon King of the West fought in a war between each other to gain power. The King of the East could see that he was losing, so he ordered his son, Choribdongi, to find Wang Janggun. Wang was a giant, son of Cheonhwang Jeseok a minor diety and Jiwang Jeseok a minor earth goddess. Choribdongi promised Wang all the treasures of the sea if he would come to the Dragon Palace. Yet, Wang refused for he had a terrible fear of the water. He then promised Wang the highest government position, but Wang refused once again. So then he promised Wang would marry the daughter of the Dragon King. Wang accepted, but Choribdongi had to promise to create a path in the water for him to enter.
In the Sea Palace, the Dragon King of the East told Wang that he planned to retreat tactically in battle, and the Dragon King of the West will leap in joy. At that moment, Wang would shoot the Dragon King of the West in the golden scale beneath his ear. The golden scale is so strong that even lightening could not break it, but the Giant pierced it easily. The West King died and his palace was destroyed.
The Dragon King of the East told Wang to choose anything in the palace, and Choribdongi whispered that the daughter was hidden in an old writing box. Everyday he would go out and log, and when he would return a meal would be ready for him. One day, he pretended to leave, but hid. When she came out, he proposed to her. Together they had three sons, Geon, Bin, and Sarang. One day she left he family and went home. Her husband became the God of War in China, and her three sons became the Gods of War in Korea, Japan, and the Middle East. They would decide who would win in battles.
Learn more here: www.blackdrago.com/history/dragonkings.htm
Check out Zhang Wang here: http://blog.sina.com.cn/nkzhangwang